PBRM1 and cancer: Among the six SWI/SNF genes, ARID1A and SMARCB1 were, respectively, the most and least frequently mutated genes in the majority of the cancer types (ARID1A, 10.7%; SMARCA4, 6.0%; ARID1B, 4.7%; ARID2, 4.0%; PBRM1, 3.5%; SMARCB1, 1.3%; Table 2, Additional file 1: Figure S1a).