SMARCA4 and hepatocellular carcinoma: 141). The SWI/SNF complex is a complex macromolecular assembly comprising 12–15 subunits, prominently featuring a catalytic ATPase subunit known as SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily A, member 4 (SMARCA4). Other subunits include adenosine thymine (AT)-rich interaction domain 1A (ARID1A), ARID1B, polybromo 1 (PBRM1) and ARID2 (Ref. 142). In HCC, mutations that inactivate SWI/SNF subunits, including ARID1A, ARID1B, ARID2, PBRM1 and SMARCA4, are frequently observed (Ref. 141).