CDKN2A and neoplasm: DNA methylation of p16/INK4A promoter CpG islands can also suppress p16/INK4A expression, and treatment of these DIPG tumor cells with a DNA methyltransferase inhibitor restored p16/INK4A transcripts to WT levels, suggesting that DNA methylation plays a more important role than EZH2 in regulation of p16/INK4A expression in these tumors [83,85].