To further investigate whether PIWIL1 was regulated by estrogen-ERα signaling in endometrial cancer, we analyzed the expression of ERα and PIWIL1 in the 30 endometrial cancer samples (15 ERα-positive endometrial cancer samples and 15 ERα-negative endometrial cancer samples) used immunohistochemistry. This evidence concerns the gene PIWIL1 and endometrial cancer.