LtfCre0/+; (Gt)R26Pik3ca*H1047R; Arid1afl/fl mice (henceforth, PIK3CA/ARID1A mutant mice) develop endometrial hyperplasia and myometrial invasion with features of endometrioid carcinoma, which can also develop an endometriosis phenotype following uterotubal incision surgery [20, 46]. The gene discussed is PIK3CA; the disease is endometriosis.