METTL9 and hepatocellular carcinoma: To investigate the potential oncogenic role of METTL9 in HCC, we first assessed the mRNA and protein expression levels of METTL9 in various HCC cell lines (HepG2, PLC-8024, Hep3B, Huh7, LM3, and MHCC97H) and normal hepatocytes (MIHA).