CCL2 and acquired polycythemia vera: In polycythemia vera, patients demonstrate increased levels of IL-1RA, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12, IL-13, IFN-γ, GM-CSF, MCP-1, MIP-1α, MIP-1β, HGF, IP-10, MIG, MCP-1, PDGF-BB, TNF-α, IFN-γ, and VEGF [25, 26].