Fig. 1.

Involvement of Abl PxxP motifs in regulating filopodium formation during attachment. A. Expression of c-Abl and variants in Abl DKO cells detected by western blotting with anti-Abl antibody (K-12, recognizing a.a. 521-531 in kinase domain (Woodring et al., 2001)) which binds equally to wt and mutated forms of Abl used in this study (data not shown). Numbers on the left side of blots indicate relative molecular mass in kDa. B. Serum-starved Abl DKO cells stably expressing various forms of Abl were plated on coverslips coated with 10 μg/ml fibronectin, and fixed at 20 minutes. The fixed cells were stained for DNA (blue), F-actin (red), and c-Abl (green) with Hoechst 33342, phalloidin/Texas-red, and anti-Abl (8E9)/Alexa-fluora 488, respectively. White bar = 10 μm. C. The number of filopodia was counted from the fixed Abl DKO cells. Graph represents mean and standard error of mean (S.E.M.) of filopodia per cell. The numbers over the bars indicate the number of cells examined. ‡ indicates P<0.05 when compared with Abl DKO cells re-expressing c-Abl.