PTGER4 and hepatocellular carcinoma: Though RAC2 (20), GNB4 (21), PTGER4 (22, 23), CCNE2 (24), FZD8 (25), TGFB3 (26), LAMA2 (27), and GSTM1 (28, 29) have been reported to be regulated by methylation in multiple cancers, very little is known about the regulatory mechanisms by which methylation is involved in HCC.