AMD3100 mobilizes MM cells and CD34⁺ HSCs in different kinetics and does not induce cytotoxicity of hematopoietic progenitor cells. (A) Mobilization of MM.1S, MM patient sample CD138⁺, and MM patient sample CD34⁺ cells after daily treatment of AMD3100 (5 mg/kg) detected by in vivo flow cytometry. AMD3100 induced similar and continuous mobilization of MM.1S and patient sample CD138⁺ cells at days 2, 3, and 4, whereas CD34 mobilization occurred on day 1 and decreased at days 2 and 3. (B) Colony-forming assays show that treatment with AMD3100 (50 μM), bortezomib (5 nM), or their combination had no significant cytotoxic effect on colony-forming units of erythroid (E), granulocyte-macrophage (MG), macrophage (M), and granulocyte-erythrocyte-monocyte-megakaryocyte (GEMM) origin. *P = .002. Error bars represent SD.