CCL2 and neoplasm: Macrophages secreted variety of cytokines at different stages, including interleukins (IL1A, IL1B, IL23A, IL20, IL10, IL6, and IL15) for regulating immune responses and inflammatory reactions at the early stage of the tumor, followed by growth factors (CXCR4, TGFB1, VEGFA, and TNFRSF10D) for supporting tumor growth, and finally chemokines (CXCL5, CXCL9, CXCL10, CXCL16, CCL2, CCL4, CCL5, CCL8, and CCL18) for promoting tumor cell migration and invasion by inducing epithelial‐mesenchymal transition (Figure 3e).