PIWIL1 and endometrial cancer: We found that the percentage of methylated CpG dinucleotides in Ishikawa, RL95–2 and HEC-1B was 45.83, 40.00 and 86.67%, respectively (Fig. 6b), suggesting that the reactivation of PIWIL1 expression in endometrial cancer is associated with hypomethylation of the PIWIL1 promoter.