In this study, we showed that the expression of SET1, WDR5 and ASH2 proteins in HepG2 and Huh-7 cells were all significantly down-regulated by silencing of MKL1 gene expression, which convincingly verified the effects of MKL1 protein in regulating the COMPASS complex functions in context of hepatocellular carcinoma. This evidence concerns the gene SETD1A and hepatocellular carcinoma.