Cdc42 controls microtubule stabilization and polarity via CD11b clustering. (A) Immunofluorescence of CD11b and microtubules of neutrophils stimulated with fMLP and plated on Fg-coated slides. Cells showing microtubules-CD11b contacts were enumerated, *P = .0062. (B) Immunofluorescence of F-actin and microtubules of WT and CD11b^−/− neutrophils stimulated with fMLP on glass. Data are representative of 3 independent experiments (scale bar, 10 μm). (C) Immunofluorescence of F-actin and microtubules of neutrophils stimulated with fMLP and plated on Fg-coated slides or on slides coated with anti-CD11b to induced CD11b clustering. Cells with more than 1 protrusion were enumerated (**P = .00067 and .0045). (D) Western blots of WCL from cells that were stimulated on Fg or CD11b coated plates, were probed with Glu-tubulin for stabilized microtubules. In fluorescence images tubulin was stained with secondary antibody conjugated with Alexa Fluor 488, while F-actin and CD11b were labeled with Rhodamine Phalloidin and secondary antibody conjugated with Alexa Fluor 594 respectively, slides were mounted in SlowFade Gold Antifade. Fluorescence images were captured at room temperature using a Leica DMI6000 fluorescence microscope at 63× objective N/A1.3 with ORCA-ER C4742-95 camera driven by Openlab Version 5.5.0 software.