ARID1A and undifferentiated carcinoma: Loss of BRG1 and/or INI1 expression has been reported in undifferentiated carcinoma and the undifferentiated component of dedifferentiated carcinomas 125,134; loss of another subunit of the SWI/SNF complex, BAF250a (the protein product of ARID1A) is common in both low-grade and high-grade endometrial carcinomas 137,138.