PTGS2 and skin cancer: An intrinsic mechanism seems to target non-melanoma skin cancer cells through AEA, which through metabolization by COX-2, becomes an apoptosis-inducing factor; the increase of AEA production appears to amplify the apoptotic results, and the effects are selective towards tumor cells since they express higher levels of COX-2 than surrounding non-tumoral keratinocytes [184,185].