Consistently, immunocytochemical staining analyses using a phospho-specific antibody, revealed that phosphorylation of EZH2 at Ser21 remarkably decreased in HCC cells treated with sorafenib and regorafenib (Fig. 4C), suggesting augmented enzymatic activity of EZH2 upon sorafenib treatment. The gene discussed is EZH2; the disease is hepatocellular carcinoma.