FIGURE 7.

Rap1GAP overexpression blocks the activation of Rap1 by CCK, carbachol, and VIP. Acini were infected overnight with adenovirus expressing either β-galactosidase (vector control) or Rap1GAP and then stimulated with 300 pm CCK (A), 10 μm carbachol (CCh), and 10 nm VIP (B) for 10 min. An inhibition of Rap1 activation was observed when the Rap1GAP-overexpressing acini were stimulated with CCK, carbachol, and VIP. The upper panel shows a representative immunoblot for GTP-Rap1, total Rap1, or Rap1GAP. The lower panel shows the quantitative analysis of Rap1 activation. Data shown are means ± S.E. (four experiments) for activation of Rap1 expressed as a percentage of basal. ^**, p < 0.01; ^***, p < 0.001 versus basal; ††, p < 0.01; †††, p < 0.001 versus CCK, carbachol, or VIP. C, to study the specificity of Rap1GAP, another set of acini were stimulated with 1 nm CCK, and then a RhoA pull-down assay was carried out; Rap1GAP overexpression did not affect CCK-induced RhoA activation. The upper panel shows a representative immunoblot for GTP-RhoA, total RhoA, or Rap1GAP. The lower panel shows the quantitative analysis of RhoA activation. Data shown are means ± S.E. (three experiments) for activation of RhoA expressed as a percentage of basal. ^*, p < 0.05 versus basal.