PTGS2 and melanoma: Cyclooxygenase-2 (COX-2) and phosphatidylinositol 3-kinase (PI3K)-AKT signaling are implicated in the radioresistance of melanoma cells, and their respective inhibitors, NS-398 and LY294002, increased the percentage of G2/M-arrested cells and decreased clonogenic survival after γ-irradiation of melanoma cells (29).