Survival after leukemia induction (B6 → B6D2F1). Wild-type B6 or pfp^−/− donors were injected with G-CSF for 6 days. Total body irradiated B6D2F1 recipients received 1 × 10⁷ splenocytes plus 25,000 p815 tumor cells from G-CSF–mobilized B6 donors (n = 10) or from G-CSF–mobilized pfp^−/− donors (n = 10) or control B6D2F1 donors (n = 5). Survival was monitored daily until day 70 posttransplantation. *P < .001 v recipients of splenocytes from G-CSF–mobilized pfp^−/− donors and control B6D2F1 donors.