BAR domain deletion caused constitutive cell collapse, and Sema3E treatment enhanced the collapse. (A) Overexpression of SH3BP1ΔBAR led to changes of cell morphology in HUVECs. SH3BP1-HA, SH3BP1ΔGAP-HA, SH3BP1ΔSH3-HA, and SH3BP1ΔBAR-HA were overexpressed in HUVECs, and cells were stained with DTAF (green) and HA antibody (red). Deletion of the BAR domain caused changes in cell morphology and size compared with full-length SH3BP1 as well as GAP and SH3 deletion. Bar, 100 µm. (B) Quantification of overexpression experiments is shown. *, P < 0.01; n = 4. Error bars indicate SEM. (C) Deletion of the BAR domain of SH3BP1 partially rescued SH3BP1 siRNA inhibition of Sema3E-induced collapse. Rescue experiments with SH3BP1ΔBAR, SH3BP1ΔSH3, and SH3BP1-Res (full-length siRNA resistant) constructs are shown. Cell shape, DTAF (green); vector expression, HA antibody (red). Arrows, cell collapse. Bar, 100 µm. (D) The results from C were quantified and the percentage of cells collapsed is shown. *, P < 0.01; **, P < 0.001. n = 4. Error bars indicate SEM.