RB1 and neoplasm: Moreover, the importance of aberrant DNA methylation of CpG island promoter regions in the pathogenesis of gliomas, oligodendrogliomas, ependymomas and pituitary adenomas is highlighted by the observation of hypermethylation of a wide variety of genes associated with tumor suppression (RB1, VHL, EMP3, RASSF1A, CITED4, BLU), cell cycle regulation (p16INK4a, p15INK4b), DNA repair (MGMT, hMLH1), and tumor invasion and apoptosis (DAPK, TIMP3, CDH1, SOCS3) [13-24].