CCL20 and neoplasm: Macrophage inflammatory protein-3α (MIP-3α), encoded by the CCL20 gene, is a chemokine that induces leukocyte migration into inflammation sites and regulates leukocyte trafficking through lymphoid tissues; and its expression has effects on tumor cell proliferation, angiogenesis, inflammatory cell infiltration, invasion, and metastasis.7 Lysosomal cysteine proteases (cathepsins) may degrade extracellular matrix, which is a key step for tumor cells breaking through the basement membrane and then causing invasion and metastasis.