Using a very interesting model for instability in leukemic cells, Messina and colleagues have found an aberrant expression of activation-induced cytidine deaminase (AICDA) in BCR/ABL1+ B-ALL [74] that upregulate DNA repair/replication and cell cycle genes, and suggested its participation in the genetic instability of BCR/ABL1+ B-ALL. Here, AICDA is linked to acute lymphoblastic leukemia.