YK11 (CAS# 1370003-76-1) is a molecule with sterol skeleton similar to dihydrotestosterone (DHT). YK11 is not yet researched in humans, not much is kno
wn about it. YK 11 has a dual (selective male sex hormone receptor modulator / myostatin antagonist) mechanism of action. In addition to being a partial agonist of androgen receptor, it is an inducer of follistatin [1]. Follistatin is an
antagonist of myostatin, a protein that inhibits muscle growth [2]. Follistatin is a protein that is part of inhibin-activin-follistatin endocrine axis that has many roles in both male and female organisms but is a major regulator of menstrual cycle in women. Follistatin is also highly expressed in skin. While main pathway resulting from androgen receptor activation is activation of specific parts of genome, the mechanism of YK11 is mainly the rapid, non-genomic mechanism [3] that has a marked effect on bone tissue growth. It may well be speculated that main mechanism is that of myostatin antagonism rather than mimicking certain aspects of male sex hormone. Before animal studies, even some basic questions remain unanswered.