CEACAM5 and cancer: In vitro activation of PPARG by its ligands correlates with increased expression of carcinoembryonic antigen (CEA), E-cadherin, developmentally regulated GTP-binding protein 1 (DRG), alkaline phosphatase, or keratins, all of them being molecules expressed in well differentiated cells, opposing to the undifferentiated cell state commonly found in most cancers [48, 64, 75–77].