Increased tumor growth occurs independently of neutrophil mobilization. (A) C57BL/6, BALB/c, OPG^Tg, and OPG^Tg wild-type littermate mice (C57BL/6.129) were administered 200 μg/kg G-CSF (n = 3 each genotype) or vehicle (n = 3 each genotype) daily for 8 days. After treatment (24 hours), blood was collected and a CBC was performed to confirm G-CSF–induced mobilization of neutrophils. All genotypes mobilized neutrophils upon G-CSF administration compared with vehicle (P = .01, C57BL/6; P = .04, BALB/c; P = .02, C57BL/6.129; P = .006, OPG^Tg). (B) C57BL/6 mice were administered 5 mg/kg AMD3100 (n = 3) or vehicle (n = 3) for 3 days. After the final dose (3 hours), blood was collected and a CBC was performed to confirm AMD3100-induced neutrophil mobilization. AMD3100-administered mice mobilized neutrophils compared with vehicle (P < .005). (C) DEXA was used to measure BMD on formalin-fixed bones of C57BL/6 mice administered AMD3100 or drug vehicle. No difference in BMD was seen in bones from mice administered AMD3100 (n = 10) compared with vehicle-administered (n = 10) animals (P = .42). (D) C57BL/6 mice were administered 5 mg/kg AMD3100 or vehicle subcutaneously for 3 days. After the first dose (3 hours), 10⁴ B16-FL tumor cells were injected into the right tibia. Tumor burden was assessed by bioluminescence imaging at days 8, 10, and 12 after tumor cell injection. No increase in tumor burden was seen in the AMD3100-administered (n = 4) mice compared with the vehicle-administered (n = 5) animals (P = .74). All error bars represent standard error of the mean. Asterisks denote statistical significance.