Fig. 5. Effects of N17Cdc42, N17Rac1 and WtRac1 on BMMs. (A) Quantification of the ruffling response to CSF-1. CSF-1-starved control (Wt or WtCre) or Rac1^–/– cells were microinjected with 100 ng/µl Flag-tagged N17Cdc42, N17Rac1 or WtRac1 cDNA, as indicated below each bar. The cells were incubated for 3 hours prior to re-stimulation with 30 ng/ml CSF-1 for 5 minutes. Following stimulation, the cells were fixed and stained for F-actin. The ruffling response to CSF-1 was scored as described in Materials and Methods. Black bars, uninjected control and Rac1^–/– cells. (B-E) Ruffling response in microinjected Rac1^–/– cells. Cells were microinjected with 100 ng/µl Flag-tagged N17Cdc42 or WtRac1 cDNA. The cells were incubated for 3 hours prior to re-stimulation with 30 ng/ml CSF-1 for 5 minutes. Following stimulation, the cells were fixed and stained for F-actin. Arrows indicate membrane ruffling. Scale bar: 10 µm. (F) Quantification of cell elongation ratio following exogenous expression of N17Rac1 and WtRac1 as described above. The elongation ratio (ratio of the longest to the shortest cell axes) was then measured (see Materials and Methods). The results shown are mean±s.e.m. of 60 cells from each population over at least three separate experiments. Statistical significance compared to WtCre values was calculated using Student's t-test, ^***P<0.001.