A total of 45%–48% of B cell precursor acute lymphoblastic leukemia (BCP-ALL) PDX models contain canonical focal deletions of the tumor suppressors on chromosome 9p, CDKN2A or CDKN2B (Figures 2A and S4B), the majority of which are homozygous. Here, CDKN2B is linked to acute lymphoblastic leukemia.