CCR2 and renal fibrosis: Cytl1 may also mediate the TGF-β-Smad signal pathway,[30] which plays a crucial role in inflammation and renal fibrosis.[31] MCP-1 exhibits the highest activity in ligands that bind to CCR2.[26] The combination of CCR2 and MCP-1 was most effective in transducing downstream signaling.[25] CCR2 consists of a C-terminus, 3 intracellular and 3 extracellular hydrophilic loops, 7 helical transmembrane domains, and an acidic N-terminus.