Upon expansion of abnormal tumor blood vessels, hypoxic microenvironment in tumors leads to the upregulation of chemokine (C-C motif) ligand-22 (CCL-22) and chemokine (C-C motif) ligand-28 (CCL-28), which are both involved in the recruitment of Tregs into tumors (71, 72). The gene discussed is CCL22; the disease is neoplasm.