CREBBP and acute myeloid leukemia: Since the long mRNA sequence of CBP (~7.5 k base pairs) hinders the stable expression of mutant CBP in MLLr-AML cells via lentivirus-based techniques, we generated a truncated CBP lacking amino acids 1-1092 (CBPΔ) compared to the full-length CBP (Supplementary Fig. S6H).