Figure 5.

Both actin-binding sites of SH2B1β are required for maximal GH-induced membrane ruffling. A–F, 3T3 F44A cells expressing GFP or the indicated forms of myc-tagged forms of SH2B1β were serum deprived (A, C, and E) and treated with 500 ng/ml GH for 10 min (B, D, and F). F-actin was visualized by staining with phalloidin-rhodamine (shown), and the transfected cells were visualized by staining with α-myc. Arrows indicate ruffles, and asterisks denote transfected cells. Scale bar, 50 μm. G, Ruffling index as the number of ruffles per cell was counted. Bars represent mean ± se. *, P < 0.05 compared with cells expressing GFP and treated with GH. Δ150–200 and Δ615–670 are designated as Δ150 and Δ615, respectively. Each experiment was repeated three times; 100 cells were assessed for ruffling in each experiment for each type of transfection.