CCL2 and hepatocellular carcinoma: Zhou et al. identified TANs as the primary source of CCL2 and CCL17 in HCC driving the recruitment of macrophages and CCR4+ Treg cells, respectively, to the tumor site (9) In contrast, Spary et al. found that fibroblast-derived CCL2 promoted the migration of monocytes in prostate cancer (86).