CCL2 and melanoma: Importantly, Natural Killer (NK) cell infiltration in melanoma positively correlates with tumor regression, as their production of tumor necrosis factor-α (TNF-α), interleukin 10 (IL-10), CCL2 (MCP-1), CCL3 (MIP1-α) crucially recruits other hematopoietic cells in areas of inflammation favoring immune recognition [16].