CLDN4 and endometrial carcinoma: However, a second study by Tessier-Cloutier et al., 2018, looking at dedifferentiated and undifferentiated endometrial carcinomas, found frequent lack of CLDN4 expression despite having a known epithelial origin, suggesting that CLDN4 may not be used to infer epithelial origin in undifferentiated endometrial tumors (Tessier-Cloutier et al., 2018).