PIWIL4 and lung adenocarcinoma: The expression of the 5 other genes were found to be repressed by over-expressed non-coding RNA or by aberrant methylation of the promoter: GALNT5 in gastric cancer [54], ADAM6 in lung adenocarcinoma [55], PIWIL1 and PIWIL4 in lung adenocarcinoma [56] and renal cell carcinoma [57].