fos activation Serum starved HepG2 cells were incubated with 10 ng/ml EGF for the indicated times. Whole cell lysates were prepared with lysis buffer V19 and separated by SDS-PAGE (ca 20.000 cells/lane). Immunoblots were probed with mab fos-34E4 (0.5 ug/ ml) for 1h at room temperature and developed by ECL (exp. time: 30 sec). lane 1: control; lane 2: 5 min EGF; lane 3: 15 min EGF; lane 4: 30 min EGF; lane 5: 1h EGF;lane 6; 2h EGF lane 7: 4h EGF; lane 8: 8h EGF