{"product_id":"yk-11-s-23","title":"YK-11 + S-23","description":"\u003cdiv class=\"qMYqUG_convSearchResultHighlightRoot\"\u003e\n\u003cdiv class=\"\"\u003e\n\u003csection class=\"text-token-text-primary w-full focus:outline-none has-data-writing-block:pointer-events-none [\u0026amp;:has([data-writing-block])\u0026gt;*]:pointer-events-auto R6Vx5W_threadScrollVars scroll-mb-[calc(var(--scroll-root-safe-area-inset-bottom,0px)+var(--thread-response-height))] scroll-mt-[calc(var(--header-height)+min(200px,max(70px,20svh)))]\" dir=\"auto\"\u003e\n\u003cdiv class=\"text-base my-auto mx-auto pb-8 [--thread-content-margin:var(--thread-content-margin-xs,calc(var(--spacing)*4))] @w-sm\/main:[--thread-content-margin:var(--thread-content-margin-sm,calc(var(--spacing)*6))] @w-lg\/main:[--thread-content-margin:var(--thread-content-margin-lg,calc(var(--spacing)*16))] px-(--thread-content-margin)\"\u003e\n\u003cdiv class=\"[--thread-content-max-width:40rem] @w-lg\/main:[--thread-content-max-width:48rem] mx-auto max-w-(--thread-content-max-width) flex-1 group\/turn-messages focus-visible:outline-hidden relative flex w-full min-w-0 flex-col agent-turn\"\u003e\n\u003cdiv class=\"flex max-w-full flex-col gap-4 grow\"\u003e\n\u003cdiv dir=\"auto\" class=\"min-h-8 text-message relative flex w-full flex-col items-end gap-2 text-start break-words whitespace-normal outline-none keyboard-focused:focus-ring [.text-message+\u0026amp;]:mt-1\" tabindex=\"0\"\u003e\n\u003cdiv class=\"flex w-full flex-col gap-1 empty:hidden\"\u003e\n\u003cdiv class=\"markdown prose dark:prose-invert wrap-break-word w-full dark markdown-new-styling\"\u003e\n\u003ch2 class=\"PDq2pG_selectionAnchorContainer\"\u003eYK-11 (Myostine) + S-23 (Mastorin) | SARMs Research UK\u003cspan class=\"PDq2pG_selectionAnchor\"\u003e\u003c\/span\u003e\n\u003c\/h2\u003e\n\u003ch2\u003eMyogenic Growth Pathway Research Set\u003c\/h2\u003e\n\u003cp\u003eThe BioPlex Myogenic Growth Pathway Research Set combines YK-11 (Myostine) 50×15mg and S-23 (Mastorin) 50×15mg, bringing together two experimental compounds associated with androgen-receptor research while offering distinctly different scientific profiles. The set contains one pot of each compound and provides a structured pairing for comparative laboratory investigation of androgen-receptor signalling, myogenic pathways and compound-specific molecular responses.\u003c\/p\u003e\n\u003cp\u003eYK-11 occupies an unusual position within the wider SARM research category. It is commonly grouped with selective androgen receptor modulators because research has demonstrated androgen-receptor-related activity, but its structure and available experimental evidence distinguish it from more conventional non-steroidal SARMs. Particular research interest has developed around its reported relationship with myogenic signalling and follistatin-associated observations, although these findings originate  primarily from limited cellular research and require careful interpretation.\u003c\/p\u003e\n\u003cp\u003eS-23, commonly known as Mastorin, is an experimental non-steroidal selective androgen receptor modulator investigated principally through androgen-receptor pathways. Its research profile therefore provides a useful comparison with YK-11, allowing two compounds associated with the same broad receptor system to be examined while recognising significant differences in their molecular structures and evidence bases.\u003c\/p\u003e\n\u003cp\u003eThe Myogenic Growth Pathway Research Set name reflects the scientific theme connecting the compounds rather than guaranteeing any particular experimental result. Myogenic signalling involves a complex network of receptors, transcription factors and regulatory proteins, and findings from one experimental system cannot automatically be transferred to another.\u003c\/p\u003e\n\u003cp\u003eBringing YK-11 and S-23 together consequently creates a research pairing centred on androgen-receptor biology while allowing YK-11's additional myogenic research questions to be considered separately. Both products remain individually identified 50×15mg capsule compounds supplied strictly for laboratory, analytical and educational research.\u003c\/p\u003e\n\u003ch2\u003e\u003cbr\u003e\u003c\/h2\u003e\n\u003ch2\u003eHow YK-11 and S-23 Work Together\u003c\/h2\u003e\n\u003cp\u003eYK-11 (Myostine) and S-23 (Mastorin) are both associated with androgen-receptor research, providing the principal scientific connection between the compounds. The androgen receptor is a ligand-regulated nuclear receptor capable of influencing transcription of androgen-responsive genes following interaction with an appropriate ligand. Differences between individual ligands can nevertheless result in substantially different experimental profiles.\u003c\/p\u003e\n\u003cp\u003eS-23 fits more conventionally within the non-steroidal selective androgen receptor modulator category. Research involving the compound has focused on androgen-receptor activity and downstream responses across experimental models. YK-11 is more unusual. Although it demonstrates androgen-receptor-associated activity, its steroidal structural characteristics and limited evidence base mean it should not simply be treated as equivalent to conventional SARMs.\u003c\/p\u003e\n\u003cp\u003eThe additional research interest surrounding YK-11 comes from cellular studies examining myogenic differentiation and follistatin-associated expression. Follistatin is a regulatory protein capable of interacting with members of the transforming growth factor-beta superfamily, including activin-related signalling pathways. This has contributed to wider discussion of YK-11 in relation to myostatin-associated research, but the distinction between observed cellular findings and established whole-system effects is essential.\u003c\/p\u003e\n\u003cp\u003ePairing YK-11 with S-23 therefore provides a framework for studying shared androgen-receptor biology alongside potentially different downstream signalling characteristics. Researchers may compare receptor-associated responses, transcriptional markers and predetermined cellular endpoints while separately examining YK-11-specific hypotheses involving myogenic regulatory pathways.\u003c\/p\u003e\n\u003cp\u003eThe combination does not establish that the compounds are synergistic or that one enhances the activity of the other. Their different molecular characteristics, evidence levels and experimental histories make controlled comparison more appropriate than assuming a predetermined combined response.\u003c\/p\u003e\n\u003cp\u003eThe research value of this pairing therefore lies in investigating two distinct androgen-receptor-associated compounds within a common experimental framework while maintaining clear separation between established receptor pharmacology, preliminary cellular findings and hypotheses requiring further investigation.\u003c\/p\u003e\n\u003ch2\u003e\n\u003cbr\u003eYK-11 (Myostine) 50×15mg\u003c\/h2\u003e\n\u003cp\u003eYK-11, commonly known as Myostine within the research-compound market, is an experimental androgen-receptor-associated compound that has attracted particular interest because of its unusual pharmacological and structural characteristics. Although frequently placed within the SARM category, YK-11 differs structurally from many better-known non-steroidal selective androgen receptor modulators and has a considerably smaller direct evidence base.\u003c\/p\u003e\n\u003cp\u003eLaboratory research has demonstrated androgen-receptor-associated activity, making receptor signalling an important part of YK-11 investigation. However, much of the wider scientific interest surrounding the compound originates from cellular research examining myogenic differentiation and associated regulatory pathways rather than extensive clinical investigation.\u003c\/p\u003e\n\u003cp\u003eOne frequently discussed area involves follistatin. Cellular research has reported changes in follistatin expression following YK-11 exposure under specific experimental conditions. Follistatin participates in complex signalling networks and can bind selected members of the TGF-beta superfamily. This relationship has led YK-11 to become widely discussed in connection with myostatin-related research.\u003c\/p\u003e\n\u003cp\u003eThat interpretation requires caution. Evidence of altered follistatin expression in a cellular model does not establish that YK-11 directly blocks myostatin or produces a predetermined tissue response across different biological systems. Myogenesis involves multiple interacting signalling pathways, transcription factors and regulatory proteins. Experimental model, concentration, exposure duration and endpoint selection can materially affect results.\u003c\/p\u003e\n\u003cp\u003eThis limited evidence base is one reason YK-11 is scientifically interesting within the Myogenic Growth Pathway Research Set. Rather than presenting hypotheses as established facts, researchers can examine its androgen-receptor-associated characteristics alongside selected myogenic markers and compare those observations with a more conventional SARM-category compound such as S-23.\u003c\/p\u003e\n\u003cp\u003eWithin this set, YK-11 therefore provides the myogenic-signalling-focused side of the pairing while retaining its relationship with wider androgen-receptor research.\u003c\/p\u003e\n\u003ch2\u003e\u003cbr\u003e\u003c\/h2\u003e\n\u003ch2\u003eS-23 (Mastorin) 50×15mg\u003c\/h2\u003e\n\u003cp\u003eS-23, commonly known as Mastorin within the research-compound market, is an experimental non-steroidal selective androgen receptor modulator studied principally for its interaction with the androgen receptor. Its pharmacological classification places it within the genuine SARM research category, distinguishing it from related compounds sometimes sold alongside SARMs that instead target completely different molecular pathways.\u003c\/p\u003e\n\u003cp\u003eThe androgen receptor functions as a ligand-activated nuclear receptor and transcriptional regulator. Following interaction with an appropriate ligand, receptor conformation and co-regulatory interactions can change, potentially altering transcription of androgen-responsive genes. S-23 research is therefore centred primarily on this receptor system and downstream experimental responses associated with its modulation.\u003c\/p\u003e\n\u003cp\u003eS-23 remains an investigational compound. Its research history includes preclinical investigation, but this does not establish approved applications or allow observations from experimental models to be generalised beyond the conditions studied. Concentration, exposure, tissue environment, receptor expression and experimental methodology remain important variables when interpreting findings.\u003c\/p\u003e\n\u003cp\u003eWithin this set, S-23 provides an interesting counterpart to YK-11. Both compounds are associated with androgen-receptor research, but their molecular characteristics and evidence profiles differ. YK-11 has generated additional research interest around myogenic and follistatin-associated observations, whereas S-23 provides a more conventional selective androgen receptor modulator framework.\u003c\/p\u003e\n\u003cp\u003eThis distinction allows researchers to consider common androgen-receptor signalling while examining whether compound-specific molecular characteristics correspond with different downstream observations. It also prevents the broad SARM classification from obscuring meaningful differences between the two molecules.\u003c\/p\u003e\n\u003cp\u003eWithin the BioPlex Myogenic Growth Pathway Research Set, S-23 therefore provides the second androgen-receptor-focused component of a comparative research pairing and complements the more specialised myogenic research questions associated with YK-11.\u003c\/p\u003e\n\u003ch3\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3\u003eExplore Related Research Compounds\u003c\/h3\u003e\n\u003cp\u003eContinue exploring related androgen-receptor and SARMs-category research compounds from BioPlex.\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/collections\/sarms\" title=\"YK-11 Myostine | Research SARM Capsules | BioPlex UK\"\u003eView YK-11 Myostine 50×15mg Research Capsules ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/collections\/sarms\" title=\"S-23 Mastorin | Research SARM Capsules | BioPlex UK\"\u003eView S-23 Mastorin 50×15mg Research Capsules ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/products\/rad-140-tesolone-br-50x15mg\" title=\"RAD-140 Testolone | Research SARM Capsules | BioPlex UK\"\u003eView RAD-140 Testolone 50×15mg Research Capsules ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003e\u003cbr\u003e\u003c\/h3\u003e\n\u003ch3\u003eExplore BioPlex Research Information\u003c\/h3\u003e\n\u003cp\u003eAccess BioPlex SARMs guidance, compound classification and the complete research product range.\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/blogs\/sarms-research-articles-bioplex-peptides-uk\/science-research-studies-complete-guide-to-sarms-uk-research-compounds-explained-for-2026\" title=\"Complete SARMs UK Research Compound Guide 2026 | BioPlex Peptides\"\u003eRead the Complete SARMs UK Research Compound Guide ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/collections\/sarms\" title=\"SARMs Research Compounds UK | BioPlex Peptides\"\u003eExplore the BioPlex SARMs Research Range ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/collections\/all\" title=\"BioPlex Peptides | All Research Products\"\u003eView All BioPlex Research Products ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003e\n\u003cbr\u003eExplore Related Research Articles\u003c\/h3\u003e\n\u003cp\u003eContinue your research with BioPlex articles covering SARMs, androgen-receptor signalling, YK-11-related research pathways and compound classification.\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/blogs\/sarms-research-articles-bioplex-peptides-uk\/science-research-studies-complete-guide-to-sarms-uk-research-compounds-explained-for-2026?\" title=\"YK-11 S-23 and SARMs Research Guide | BioPlex Peptides\"\u003eRead the Complete Guide to SARMs UK: Research Compounds Explained ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/blogs\/sarms-research-articles-bioplex-peptides-uk\/rad-140-testolone-research-overview\" title=\"RAD-140 Testolone Androgen Receptor Research Overview | BioPlex Peptides\"\u003eRead the RAD-140 Testolone Research Overview ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/bioplexpeptides.co.uk\/blogs\/sarms-research-articles-bioplex-peptides-uk\" title=\"SARMs Research Articles | BioPlex Peptides UK\"\u003eExplore All BioPlex SARMs Research Articles ⟶\u003c\/a\u003e\u003c\/p\u003e\n\u003ch2\u003e\n\u003cbr\u003eDisclaimer\u003c\/h2\u003e\n\u003cp\u003e\u003ca title=\"Legal Notice | BioPlex Peptides UK\" rel=\"noopener\" class=\"decorated-link\" href=\"https:\/\/bioplexpeptides.co.uk\/policies\/legal-notice\"\u003eFor research purposes only. Not for human consumption\u003c\/a\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"mt-3 w-full empty:hidden has-[\u0026gt;_:empty]:hidden\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"BioPlexPeptides.co.uk","offers":[{"title":"Default Title","offer_id":58753175257472,"sku":null,"price":82.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0991\/6783\/0400\/files\/YK-11_S-23.png?v=1787432199","url":"https:\/\/bioplexpeptides.co.uk\/cs\/products\/yk-11-s-23","provider":"BioPlexPeptides.co.uk","version":"1.0","type":"link"}