Glioma cell proliferation, including glioma stem cells (Yi et al., 2011), results in the secretion of cytokines and chemokines such as MIC-1, periostin, IL-33, and MCP-1 (Wu et al., 2010; Zhou et al., 2015; Roesch et al., 2018; De Boeck et al., 2020), which recruit blood-borne monocytes and macrophages to the tumor site, polarizing them into M2 TAMs. The gene discussed is CCL2; the disease is glioma.