Interestingly, treatment with TSA, but not with DAC, could trigger JMJD5 expression in SK-HEP-1, HuH-7, YY-8103, MHCC-97H and HCC-LM6 cells (Figure 2A and Supplemental Figure 2A), implying that, although the JMJD5 promoter contains one CpG islands, it is histone modifications, not DNA methylation, that could be the major mechanism for regulating JMJD5 transcription. This evidence concerns the gene KDM8 and hepatocellular carcinoma.