FIG. 3.

Rescue of the JNK pathway by expression of wild-type Gab1 in Gab1^−/− cells. Gab1^−/− cells were transiently transfected with 1, 2, or 4 μg of the expression construct for human Gab1 cDNA, using the GenePORTER 2 transfection reagent (Gene Therapy Systems Inc.). After incubation at 37°C for 72 h, the cells were irradiated with UV-B light at 400 J/m² or left untreated. JNK activation was detected by immunoblotting (IB) using an anti-p-JNK antibody. The membrane was stripped and immunoblotted with an anti-JNK2 antibody as loading control. Exogenous expression of Gab1 in transfected cells was confirmed by anti-Gab1 immunoblot analysis with wild-type cells as positive control. +/+, wild-type cells; −/−, Gab1^−/− cells.