NBPF20 and polycystic ovary syndrome: In addition, a similar study analyzing the skeletal muscle biopsies from women with PCOS identified several differentially methylated genes involved in IR, including krüppel-like factor 10 (KLF10), COL1A1, MAP2K6, titin (TTN), and NBPF20. Insulin was found to increase KLF10 expression, while testosterone was found to downregulate the COL1A1 and MAP2K6 expression.