Phosphospecificity Whole cell extracts of control (co), EGF stim ulated (EGF) or pervanadate treated (VH) A431 tumor cells were applied to SDS-PAGE (ca 20.000 cells per lane) and transferred to PVDF membranes. Immunoblots were probed with mab GSK-9B8 (0.5 ug/ ml) for 1h at RT and developed by ECL (exp. time: 30 sec).