CCL2 and cancer: During cancer progression, cancer cell-derived CCL2, CCL5, CXCL8, and CXCL5 are released and recruit immunosuppressive-myeloid cells into the TME, including MDSCs, TAMs, and TANs through CXCR2 activation (Toh et al., 2011; Katoh et al., 2013; Xiao et al., 2015; Zhang et al., 2020b).