SMARCA1 and bladder transitional cell carcinoma: Our comprehensive SWI/SNF subunit gene analysis revealed ARID1A truncating mutations, shown to be associated with reduction in ARID1A mRNA expression levels (see Fig 1C) and ARID1A protein loss in previous studies [35,36], as the most common genetic alterations of SWI/SNF complexes in urothelial bladder cancer.