Methylation analysis indicated that the level of methylated CpG sites of BMP4 in HepG2 and Huh7 were higher than that in SMMC-7721 and Sk-Hep-1 (Figure S4B), suggesting that the methylation level of the BMP4 promoter correlates with HCC metastasis. This evidence concerns the gene BMP4 and hepatocellular carcinoma.