PPP2R1A and carcinosarcoma: However, this phenomenon was not observed in endometrial serous carcinomas which have frequent mutations in TP53 and PPP2R1A but lack mutations in PTEN, ARID1A, and CTNBB1. On the other hand, in carcinosarcoma, two distinct mutation profiles have been identified which were the endometrioid type (PTEN, PIK3CA, ARID1A, and KRAS mutations) and serous type (TP53 and PPP2R1A; McConechy et al., 2012).