The cytokines C‐C motif chemokine 2 (CCL2), macrophage colony‐stimulating factor 1 (CSF1), and growth differentiation factor 15 (GDF15) produced by tumor cells are the main regulators of macrophage infiltration and survival.[20] qPCR detection (Figure 3h–j) suggested that the mRNA expression of CCL2, CSF1, and GDF15 was dramatically decreased upon SLITRK4 knockdown, whereas SLITRK4 overexpression promoted their production. The gene discussed is CCL2; the disease is neoplasm.