Joshi et al. (51) previously reported the haploinsufficiency of PTEN in the repression of PI3K-driven mouse uterine cancers: PIK3CAE545K expression in the Müllerian duct epithelium caused pathological lesions in the adult uterus only when a copy of Pten was inactivated, and the biallelic loss of Pten in combination with PIK3CAE545K caused ECs. Here, PTEN is linked to uterine cancer.