NS398 has been one of the earliest COX-2-selective inhibitors discovered [54] and, even if not yet approved by the FDA for clinical use, it continues to be largely used, also recently, by a plethora of researchers, as a prototype COX-2 inhibitor for in vitro and in vivo studies on several types of cancers, including GBM [20,36,55,56]. Here, PTGS2 is linked to cancer.