Stroma cell-derived factor 1 (SDF-1) is known to stimulate the activation of the p38 MAPK pathway in NPC cells with downregulation of microRNA-9 (miR-9), which reportedly exhibits tumor suppressor properties, through CXCR4 overexpression, leading to NPC cell growth, migration, and invasion [82]. Here, CXCR4 is linked to nasopharyngeal carcinoma.