ERRFI1 and endometrial cancer: Further supporting a role of Gene 33 in endometrial cancer, tissue-specific knockout of Errfi1 from mouse uterine epithelium using the Wnt7a-Cre/Errfi1flox/flox approach promotes endometrial hyperplasia and estrogen-dependent endometrial cancer, indicating that epithelial Gene 33 expression is critical for the development of endometrial malignancy and that progesterone in the stroma may inhibit the neoplastic transformation of uterine epithelial cells [139].