CYP17A1 and polycystic ovary syndrome: Increased activity of CYP17 has been hypothesized to enhance androgen biosynthesis and secretion in PCOS.41 To investigate the role of S100‐A9 in steroidogenesis, the expression levels of CYP17 and CYP19A1 mRNA in KGNs were determined by qRT‐PCR.