PTGS2 and cervical carcinoma: Oh et al. studied the effects of HPV E5 protein on PGE2 signaling in cervical cancer cells and described an induction of EP4 by HPV E5 with epidermal growth factor receptor, COX-2, PGE2, EP2 and EP4, protein kinase A, CREB and CRE being engaged in this induction [36].