CXCR4 and neoplasm: Under the hypoxia condition, primary human and murine macrophages displayed the upregulation of the cell surface receptors, CXCR4 and GLUT1, and tumor-promoting cytokines VEGFA, IL-1β and IL-8, adrenomedullin, CXCR4 and angiopoietin-2, indicating the importance of both HIFs 1 and 2 in response of macrophages to hypoxia [266].