Lsc is required for normal RhoA activity in formyl-peptide–stimulated neutrophils. (A) RhoA activity (activated RhoA/total RhoA) was measured in suspended WT and Lsc KO neutrophils incubated with 10 μM fMLP for the indicated times. Data are the mean RhoA activity ± SEM normalized to the RhoA activity of unstimulated WT neutrophils from 3 independent experiments. Formyl-peptide stimulation increases RhoA activity in WT neutrophils. Formyl-peptide–stimulated RhoA activity is decreased in Lsc KO neutrophils compared with WT neutrophils. (B) Cdc 42 activity (activated Cdc42/total Cdc42) is similar in suspended WT and Lsc KO neutrophils incubated with 10 μM fMLP for the indicated times. Data are the mean Cdc42 activity ± SEM normalized to the Cdc42 activity of unstimulated WT neutrophils from 2 independent experiments. □ indicates WT; ▪, KO.