CXCL12 and neoplasm: Moreover, cell components of the hypoxic tumor microenvironment (TME) increase chemokine secretion, including stromal cell-derived factor 1-α (SDF1-α) and C-C Motif Chemokine Ligand 28 (CCL28), and recruit regulatory T helper cells (Tregs), a heterogeneous population of immature myeloid cells (MDSCs), and M2-type macrophages.