PIWIL1 and atypical endometrial hyperplasia: Consistent with our RT-qPCR analysis, the protein expression of Piwil1 was also significantly higher in endometrial atypical hyperplasia (IS = 2.9, ***P < 0.001) and endometrial cancer tissues (IS = 5.0, ***P < 0.001) compared with normal endometrial tissues (IS = 1.5, Fig. 1c).