PVR and cancer: However, PGE2 does not appear to be a primary regulator in all cancer types, as CAFs derived from endometrial cancer are able to promote NK dysfunction independent of PGE2 signaling, and instead do so by downregulating cell surface poliovirus receptor (PVR/CD155), an important DNAM-1 ligand that is normally present on endometrial fibroblasts (Inoue et al., 2016).