In HCC cells, JMJD5 may function as a co-activator via binding to the CDKN1A promoter, whereas, in MEFs, Jmjd5, binding to Cdkn1a gene body, could exert the histone demethylase activity that modifies H3K36 methylation and alters the downstream gene transcription. The gene discussed is CDKN1A; the disease is hepatocellular carcinoma.