SMARCA4 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a) is the central ATPase containing enzyme in the SWI/SNF- (switch/sucrose non-fermentable) complex, which regulates chromatin accessibility and thereby influences gene transcription. By acting as a transcriptional activator or repressor in different cell types, SMARCA4 and the SWI/SNF complex have various functions.