Mobilization and expansion. C57BL/6 mice were treated with the CXCR4 antagonists POL5551 (100 mg/kg per day for 1 or 2 weeks [wks]), AMD3100 (20 mg/kg per day for 2 weeks,), and ALT1188 (ALT; 33 mg/kg per day for 2 weeks) via subcutaneous infusion pumps. Control groups received G-CSF (100 μg/kg per dose at 4 or 9 doses every 12 hours) or phosphate-buffered saline (PBS). Concurrent analysis of hematopoiesis in PB and BM was performed. (A) WBC concentration in PB and BM. Corresponding CFU-C/LSK numbers are presented in (B) PB and (C) BM. (D) CFU-C/LSK frequency in BM, (E) LSK SLAM count, and (F) LSK SLAM frequency are shown. Representative flow cytometry analyses of LSK and LSK SLAM fraction in (G) PB and (H) BM of differentially treated mice are shown (mean ± SEM; n = 3). ***P < .001; **P < .01; *P < .05.