One of the genes that has a disputable effect on prognosis in pediatric ALL is the cyclin-dependent kinase inhibitor 2A/2B (CDKN2A/2B), located on the 9p21 chromosomal region and comprising two tumor-suppressor genes lying adjacent to each other, which encode for three proteins: (a) p16INK4A (inhibitor of CDK4), (b) p14ARF (alternative reading frame) by CDKN2A, and (c) p15INK4B by CDKN2B [17]. Here, CDKN2B is linked to acute lymphoblastic leukemia.