CDKN2A and acute lymphoblastic leukemia: Another aspect is the interdependence of p15 and p16, since some studies have shown homologous deletion of both genes in most acute lymphoblastic leukemia cases,5,6,14,18,19 while in others p16 was the only target.6,20,21 Furthermore, while deletion seems to be one of the main mechanisms of inactivation for both genes, point mutations may play an important role in p16 inactivation, while epigenetic mechanisms such as hypermethylation are also considered for p15.6,20