CCR1 and plasma cell myeloma: The data showed that the levels of CCR1 and CCR5, but not CCR4, were significantly increased on the HSPCs of myeloma patients compared to healthy donors (CCR1: 5.13% ± 1.32% vs. 0.85% ± 0.24%, p = 0.0096; CCR5: 5.72% ± 1.57% vs. 1.91% ± 0.37%, p = 0.0199; Fig. 7A).