BAF170 (SMARCC2) and BAF155 (SMARCC1) are mutated infrequently in cancers. BAF170 is mutated in gastric and colorectal cancers with microsatellite instability (86). The homologous subunit BAF155 is mutated in about 10% of small cell lung cancers (4). Both BAF155 and BAF170 are true homologs of yeast SWI3 (>20% identical over the entire length of the protein). These two members will dimerize in solution and appear to make hetero- or homodimers within the complexes in mammalian cells. Only BAF155 (and not BAF170) is expressed in pluripotent cells and is part of the specialized esBAF complex, which is essential for pluripotency in murine ES cells. The mutations seen in these proteins are scattered over the body of the gene and appear to generally inactivate the protein.
