TP53 and neoplasm: Dysregulation of the p16/RB1 or p14ARF/MDM2/p53 pathways may limit the activity of MAPK-directed targeted therapy [8] (Figure 1), and CDKN2A loss in the tumor was an independent predictor of shorter PFS BRAF-mutant metastatic melanoma patients treated in a study with the BRAFi dabrafenib as a single agent [9].