RB1 and neoplasm: Anaplastic Astrocytoma also occasionally show losses of both wild-type copies of the three tumour suppressor genes (TSGs) located on 9p, CDKN2A, CDKN2B, p14ARF (Ichimura et al, 2000), simultaneously disrupting both the Rb1 and p53 pathways, as well as loss of both wild-type copies of the PTEN gene on 10q (Schmidt et al, 1999).