MAPK14 and Insulin resistance: It is possibly attributable that metformin inhibits testosterone-induced endoplasmic reticulum stress in ovarian granulosa cells via inactivation of p38 mitogen-activated protein kinases (MAPK).[28] The mechanism by which metformin reduces testosterone levels in girls might be related to the improvement of peripheral insulin resistance.[29] In addition, high heterogeneity was detected, which might be due to different ages and administration methods.