Rap1GAP prevents collagen I–induced changes in BxPC3 cells. (A) 1 mg of protein from BxPC3 cells 4 h after plating on noncoated, collagen I–coated, or fibronectin-coated dishes was incubated with GST-Ral-GDS–coupled beads and resolved by SDS-PAGE. Rap1-GTP, total Rap1, Rap2-GTP, and total Rap2 were detected by Rap1 and Rap2 blots. The ratio of Rap1-GTP/total Rap1 is shown above the gel. (B) Mock BxPC3 cells or cells expressing Rap1GAP were cultured on noncoated (a and c) or collagen I–coated (b and d) dishes for 2 d. Bar, 100 μm. (C) Mock BxPC3 cells or cells expressing Rap1GAP were extracted and blotted for N-cadherin (a), flag (to detect Rap1GAP; b), or tubulin (c). Rap1 pulldown assays were performed as described in A (d and e). The ratio of Rap1-GTP/total Rap1 is shown (nd, none detected). (D) Mock BxPC3 cells or cells expressing Rap1GAP were extracted and blotted for p-JNK (T183/Y185) and total JNK1. The ratio of p-JNK/t-JNK is shown above the gel. Bands corresponding to p-JNK indicated (arrow).