The in vivo effect of PF4 on platelet count recovery after injection of 5-FU. (A) Mean relative change in platelet count ± 1 SD in WT (•) and mPF4^−/− (◇) animals after injection of 5-FU shown as percentage of baseline platelet count. (B) Same as in panel A, but for WT mice controls ({9I}) and hPF4×6⁺ mice (♦). (C) The same as panels A and B, but for total WBC. (D) The same as panel A, but for hemoglobin. All studies were done in triplicate with 5 to 6 mice per arm (graphs represent data from 15-18 animals per arm). *P < .03 compared with WT. **P < .003 compared with WT. Grey horizontal bar denotes 100% of baseline platelet count and is drawn to allow for easier discrimination of recovery.