The mutations in ARID1A gene encoding BAF250a subunit of the SWI/SNF CRC were found in BC, although mutations in genes coding for core subunits were identified only with low frequency.8, 22 The self‐regulation and interdependence between SWI/SNF subunits expression were already described10; therefore, we examined the abundance of three main SWI/SNF CRC subunits: BRM ATPase, BAF155, and INI1 in advanced MIBC compared with adjacent urothelium using IHC on paraffin‐embedded samples. This evidence concerns the gene ARID1A and breast cancer.