FMLP or CSF-1 induces F-actin–rich ruffles in RAW LacR/ FMLPR.2 cells. Cells were fixed and stained with rhodamine-phalloidin  as described in Materials and Methods. (a) Unstimulated. (b) Cells incubated with 100 nM FMLP for 1 min. (c) Cells incubated with 10 ng/ml  CSF-1 for 5 min. Bar = 10 μm. (d) Inhibition of FMLP-induced ruffles  by pertussis toxin (1 ng/ml for 24 h) in RAW LacR/FMLPR.2 cells.  Solid bars, − pertussis toxin; striped bars, + pertussis toxin.