EGFR activation induces AP-1 protein expression in human cancer cells. SCC25 cells were cultured in low serum medium prior to stimulation with 10 ng/ml EGF for up to 4 hours as described in Methods. Whole cell lysates were subjected to western blot analysis using anti-human primary antibodies to c-fos, Fra-1, c-jun, and JunB. These experiments were performed three times using different lysates with similar results. Representative blots are shown.