Rac1 is involved in CD44-mediated phagocytosis. (A-B) Confocal fluorescent and transmitted light images of GFP PBD-transfected RAW cells presented with CD44 Ebabs. Solid line represents 5 μm. (C) Efficiency of phagocytosis of CD44 Ebabs by RAW cells preincubated with 0 or 1 μg/mL C difficile toxin B. *Different from 0 μg/mL C difficile toxin B; P < .01, mean ± SE of 4 separate experiments. (D) Efficiency of phagocytosis of Rac1 (T17N) dominant-negative GFP-transfected RAW cells or the nontransfected controls fed with CD44 Ebabs. *Different from nontransfected controls; P < .01, n = 4. (E) Efficiency of phagocytosis of CD44 Ebabs by Rac1^–/–, Rac2^–/–, Rac1^–/–/Rac2^–/– (double knockout), and wild-type peritoneal macrophages. *Different from wild-type peritoneal macrophages; P < .01, mean ± SE of 4 separate experiments.