ERRFI1 and endometrial cancer: As P4 resistance is related to hyperactive AKT signaling in endometrial cancer cells [39,60], we performed immunohistochemistry of MIG-6 and pAKT (phospho-AKT at Ser473) in controls (n = 6) and women with early-stage EEC (n = 21) to examine whether MIG-6 and pAKT expression is correlated in early-stage EEC.