Requirement of SHP2 activity in PAF-induced pulmonary eosinophil recruitment of guinea pigs. Guinea pigs were aerosolized for 15 min with NS, 2 or 10 mg/ml PHPS1 dissolved in NS, or 10 or 50 μg/ml RMC4550 dissolved in NS. After 2 h, guinea pigs were further aerosolized with NS or PAF at 10 μg/ml for 1 h. Forty-eight hours after last aerosolization, guinea pigs were subjected to preparation of BALFs for eosinophil counting (A), whereas lungs were used for ECP determination (B) and H&E staining and histologic evaluation (C). Data are presented as means ± sd (n = 5). ++P < 0.01 vs. without PAF, PHPS1, or RMC4550; **P < 0.01, *P < 0.05 vs. 10 μg/ml PAF alone.