RB1 and neoplasm: In GBM, there is frequent hypermethylation of tumour suppressors (RB1, EMP3, RASSF1A and BLU), cell cycle regulators (p16INK4a and p15INK4b), DNA repair genes (MGMT, MLH1), and genes involved in tumour invasion and apoptosis (DAPK, TIMP3 and CDH1) (Alaminos et al., 2005; Costello et al., 1994; Fukushima et al., 2005; Gonzalez-Gomez et al., 2003; Herman et al., 1996; Hesson et al., 2004; Horiguchi et al., 2003; Nakamura et al., 2001b; Uhlmann et al., 2003).