KB cells were pre-treated for 1 hour with or without 10 μM SB 203580 or 2 μM PD184352 then simulated with H2O2 (2 mM for 15 mins), UV-C (30 mins), anisomycin (10 μg/ml for 30 mins) or sorbitol (0.5 M for 30 mins) and lthen lysed. TAB1 was immunoprecipitated using anti-TAB1 S823A, 2 μg of anti-TAB1 was incubated for 1 hour at 4 °C with 250 μg of protein lysate. The immunocomplex was denatured in SDS, separated by SDS-PAGE, transferred to nitrocellulose membrane and blotted with the appropriate phospho-specific antibody. Binding of the primary antibody was detected using rabbit peroxidase conjugated anti- sheep IgG antibody (1 in 10, 000 dilution, Pierce) followed by enhanced chemiluminescence (ECL, Amersham).