TP53 and neoplasm: Indeed, the growth of human melanoma A375 xenograft tumors was dramatically reduced upon inactivation of iPLA2β expression (2 vs. 1, Fig. 6a, b) in xenograft tumor growth assays; however, the tumor suppressive effects induced by loss of iPLA2β expression were largely abrogated when isogenic p53-null A375 cells were used (4 vs. 3, Fig. 6a, b).