In a different colon carcinoma cell line EP4 receptor was found to drive in vivo growth by augmenting tumor vascularization, and delaying apoptosis (Pozzi et al., 2004), while colon carcinogenesis was inhibited in mice lacking EP4 but not EP2 receptors, and by the EP4 antagonist ONO AE2-227 (Mutoh et al., 2002). This evidence concerns the gene PTGER4 and colon carcinoma.