CREBBP and cancer: Therefore, we propose the following molecular mechanism to explain synthetic lethality upon simultaneous inhibition of CBP and p300 in SMARCB1-deficient cancers: in SMARCB1-proficient cells, the SMARCB1-containing SWI/SNF complex suppresses transcription of KREMEN2; this suggests that SMARCB1-proficient cells are not dependent on CBP/p300 and KREMEN2 (Fig. 6m).