Melanoma-derived fibroblasts secrete factors such as C–C motif chemokine ligand 5 (CCL5), CCL2, and C-X-C motif chemokine ligand 12 (CXCL12), which induce immune checkpoint (ICP) ligand expression in melanoma cells, thereby compromising CD8+ T cell function [211, 212]. This evidence concerns the gene CCL2 and melanoma.