CREBBP and acute lymphoblastic leukemia: B-ALL relapse is frequently associated with the acquisition of drug resistance mutations in genes such as CREBBP,48NT5C2,49, 50SETD251 and others52 so we propose that the opportunity/likelihood of acquisition of such mutations increases with the number of residual B-ALL cells during remission, which is in turn determined by partial chemoresistance and/or inadequate therapy (Figure 4).