Rat MCP-1/JE (monocyte chemoattractant protein-1) is a 148-amino acid CC chemokine with a N-terminal sequence of 29 residues as a signal sequence. It was originally cloned from Con-A-stimulated rat spleen cDNA library. This rat MCP-1/JE is 49-amino acid longer than human MCP-1 at 3’-end. The 3’-end is a serine and threonine rich zone, which is probably responsible for the extensive O-glycosylation and which explains for the higher molecular weight (25 kDa). In vitro, MCP-1/JE is chemotactic for monocytes as well as lymphocytes and basophils, but not for neutrophiles. MCP-1/JE is produced by a wide range of cell types as a reaction to diverse inflammatory stimuli.