CCR1 and plasma cell myeloma: Chemokine (C-C motif) receptor 1 (CCR1) is expressed in numerous cell types and tissues, including leukocytes, endothelial cells and vascular smooth muscle cells, and is thought to play important roles in the pathogenesis of multiple disease processes, including but not limited to rheumatoid arthritis, multiple sclerosis, eosinophilic airway inflammation, and multiple myeloma [2,3,4,5,6,7].