FIGURE 7.

Osmotic stress activates c-Src by an intracellular calcium and JNK-dependent mechanism. A, Caco-2 cell monolayers were pretreated with or without SP600125 or PP2 for 30 min prior to osmotic stress. At varying times protein extracts were immunoblotted for c-Src(pY418) and total c-Src. B, OS was induced in cell monolayers pretreated with or without BAPTA-AM or isradipine (Isra) or incubated with CFM. Protein extracts at 30 min after osmotic stress were immunoblotted for Src(pY418) and total c-Src. Asterisks indicate the band density values that are significantly (p < 0.05) different from the corresponding value for the control group, and # indicates that values that are significantly different from the corresponding value for “None” in the OS group. C, proteins extracted from Caco-2 cells transfected with nonspecific RNA (NS-RNA) or c-Src siRNA were immunoblotted for c-Src and β-actin. Asterisks indicate the band density value that is significantly (p < 0.05) different from the corresponding value for the NS-RNA group (gray bar). D, Caco-2 cell monolayers transfected with NS-RNA or c-Src siRNA were exposed to osmotic stress for 1 h. Inulin permeability was measured. Values are mean ± S.E. (n = 6). Asterisks indicate the values that are significantly (p < 0.05) different from the corresponding control values. # indicates values that are significantly different from the corresponding value for the NS-RNA group. E, untreated and osmotic stress-treated cell monolayers were fixed and stained for occludin and ZO-1. F, proteins extracted from Caco-2 cells transfected with nonspecific RNA or c-Yes siRNA were immunoblotted for c-Src and β-actin. G, Caco-2 cell monolayers transfected with NS-RNA or c-Yes siRNA were exposed to osmotic stress for 1 h. Inulin permeability was measured. Values are mean ± S.E. (n = 6).