MKRN2 and Infertility: MKRN2 inhibits the p53 apoptosis effector related to PMP22 (PERP) expression, and levels of the protein in sperm samples have an inverse correlation with infertility levels, implying that MKRN2 is important for protecting germ cells from excessive apoptosis and implicating MKRN2-based suppression of the p53/PERP signaling pathway in spermatogenesis and male fertility (56).