CREBBP and acute lymphoblastic leukemia: The CREBBP wild-type (WT) B-ALL cell line 697 (derived from a patient with high-risk relapsed E2A::PBX1 B-ALL)21 was genome-engineered by CRISPR-Cas9 homologous recombination to introduce a recurrent hotspot mutation at arginine 1446 (CREBBPR1446C), which is implicated to exert a dominant-negative effect on CREBBP acetyltransferase activity4.