After treatment of human dental pulp cells with IL-1β, mostly secreted by odontoblasts and dental pulp cells in response to cariogenic infection,3 , 30 a significant induction of COX-2, but not 5-LOX, was found, suggesting that the 5-LOX pathway of arachidonic acid metabolism is not involved in an IL-1β-mediated inflammatory pulpal response. Here, PTGS2 is linked to infection.