Using monocyte-derived macrophages (MDMs) from patients with chronic obstructive pulmonary disease (COPD), Provost et al. showed that extracellular Ca could enhance phagocytosis and cytokine secretion associated with IL-8, TNF-α, and macrophage inflammatory protein (MIP) subunits MIP-1a and MIP-1b [34]. Here, CCL4 is linked to chronic obstructive pulmonary disease.