CXCR4 and lung cancer: In hypoxia, HIF-1α promotes cell migration and invasion by inducing multiple genes, including the stromal cell-derived factor-1/C-X-C motif chemokine receptor-4 (SDF-1/CXCR-4) axis, C-C motif chemokine receptor 7 (CCR7), and lysyl oxidase (LOX) in lung cancer cells [27–30].