The SMARCs (SWI/SNF-related, matrix-associated, actin-dependent regulators of chromatin), and BAFs (BRG1-associated factors), have been identified as components of the mammalian SWI/SNF-like chromatin-remodeling protein complexes. These multi-protein complexes are proposed to function as ATP-driven motors that translocate along DNA and destabilize nucleosomal structures to facilitate transcription factor binding. PBRM1 is a component of the SWI/SNF-B (PBAF) complex. It contains six bromodomains which are defined by a 110 amino-acid module that interacts with acetylated lysine and is found in many chromatin binding proteins and histone acetyltransferases. PBRM1 has been proposed to function as a tumor suppressor protein. Recently, PBRM1 has been found to play a role in mediating cell cycle arrest in response to DNA damage via the regulation of the tumor suppressor p21.