PTGS2 and skin aging: Several studies pointed the role of PTGS2 in senescence and aging of the dermis: (i) PTGS2 expression is increased in human aged skin, including fibroblasts of the dermis, compared to normal young skin [32, 33] and, in accordance, NS398, a selective PTGS2 inhibitor, has been shown to reduce skin aging in mice [34]; (ii) PTGS2 takes part in replicative senescence of in vitro cultured normal human dermal fibroblasts (NHDFs) [35], and NS398 also reduced this function [36].