Migration inhibition by L. pneumophila is augmented in the absence of Cdc42.

(A) Confluent cell layers of A549 cells were treated with (A) scrambled siRNA or siRNA against (B) Cdc42 or (C) Rac1 for 2 days, left uninfected or infected (MOI 10, 1 h) with L. pneumophila wild-type or ΔicmT mutant bacteria, scratched and let migrate for 24 h. Prior to imaging (0, 24 h), the detached cells were washed off. (B) The scratch area was quantified after 24 h at 7 different positions per condition using ImageJ software. Means and standard deviations of triplicate samples per condition are shown, which are representative of 3 independent experiments (***p L. pneumophila colocalizes with IQGAP1 and Cdc42. A549 cells were infected (MOI 10, 1 h) with L. pneumophila wild-type or ΔicmT mutant bacteria harboring plasmid pSW001 (DsRed), and the subcellular localization of the scaffold protein (green; FITC) or the small GTPase (green; FITC) was analyzed by confocal microscopy using antibodies against IQGAP1 or Cdc42. Nuclei were stained with DAPI (blue). Bars, 5 μm.