One possibility is the modulation of chemokine receptors through hypoxic conditions, which is known to induce cancer cell expression of c-Met, the bona fide receptor of HGF, and CXCR4, the signalling receptor of the chemokine CXCL12 (SDF1), and further stimulate cancer cell migration and dissemination[51,52]. The gene discussed is CXCR4; the disease is cancer.