The name CCR2 refers to two alternatively spliced chemokine receptors: CCR2A and CCR2B. Although first identified as the specific, high-affinity receptor for MCP-1 present in monocytic cell lines, other che-mokines have been shown to elicit responses through CCR2. CCR2 is expressed in monocytes, macrophages. T and В lymphocytes, natural killer (NK) cells, dendritic cells (DC), and in nonlymphoid cells and tissues. As one of the first chemokine receptors to be cloned and characterized, it has been studied extensively. Its implication in several pathologies, its structure-activity relationship, the signaling pathways activated, as well as its regulation have been analyzed in detail and it has served as a model for the study of other chemokine receptors.