FIGURE 2.

Gα₁₃ is necessary for gastrin-stimulated paxillin tyrosine phosphorylation and SRE activation. A, lysates of Mock, Gα₁₃, or Scr shRNA-expressing DLD-1 cells were immunoblotted with antibodies to Rgnef, Gα₁₂, Gα₁₃, Gα_q, and β-tubulin. B, representative paxillin IPs from lysates of Mock, Scr-, and Gα₁₃ shRNA-expressing DLD-1 cells pretreated with gastrin (200 nm, 40 min). Phosphospecific paxillin Tyr(P)-31 (pY31) was followed by detection of total paxillin levels. C, image quantification from paxillin IPs shown in B. Control was set to 1, and values are means ± S.E. for fold induction of three independent experiments. D, representative FAK IPs from lysates of Scr- and Gα₁₃ shRNA-expressing DLD-1 cells that stimulated with gastrin (200 nm, 30 min). Phosphospecific FAK-Tyr(P)-397 (pY397) was followed by detection of total FAK levels by immunoblotting. Phosphospecific paxillin Tyr(P)-31 was followed by detection of total paxillin levels by immunoblotting on the corresponding lysates. E, DLD-1 cells transduced with anti-Gα₁₃ or Scr shRNA were transfected with pSRE.L and RLuc vectors. After 24 h, cells were serum-starved and then treated with vehicle or gastrin (200 nm) for 6 h, and lysates were prepared for luciferase detection. Values were set to 1, and data are means ± S.E. fold induction (relative units, R.U.) from three independent experiments (*, p < 0.05, two-tailed t test).