Mobilization of mouse progenitor cells in NOD/SCID. (A) Progenitor cells in femur and blood of animals unirradiated or preirradiated with 300 cGy, untreated or after treatment with cyclophosphamide (200 mg/kg interperitoneally at day 6) followed by 4 days of G-CSF (250 μg/kg/d, subcutaneously). Bars indicate mean ± SEM (n = 2 per group). The difference between irradiated and nonirradiated animals was not significant (P = .07). (Note: left axis has a log scale, right axis has a linear scale.) (B) Spleen weight and (C) white blood cell (WBC) counts of the same animals (mean ± SEM, n = 2). In nonirradiated animals, the increase in both spleen weight and WBC counts is highly significant (P < .01). Increase of WBC in irradiated animals as compared with control is also highly significant (P < .01) whereas spleen weight did not change.