CDKN2A and acute lymphoblastic leukemia: Deletions of the cyclin-dependent kinase inhibitor 2A (CDKN2A encoding tumor suppressors p16INK4A and p14ARF) and 2B (CDKN2B encoding the tumor suppressor p15INK4B) loci on 9p21 are present in up to 70% of T-ALL, leading to abnormal proliferation control (70).