ARID1B and neoplasm: Due to the fact that we have previously discovered co-current mutations and protein loss of ARID1A and ARID1B, two mutually exclusive accessory components of the SWI/SNF BAF chromatin-remodeling complex [6], in DDEC and UEC [9, 13], we determined the protein expression of ARID1A and ARID1B in both primary tumor and xenograft tumors by IHC.