Fig. 2

Caspase inhibitor blocks stress-induced degradation but not EGF (ligand)-induced degradation of EGFR. HeLa cells were cultured and serum-starved the same as described in Fig. 1. The caspase inhibitor mix (the caspase inhibitor mix, 2 μM each), Caspase-3 inhibitor (20 μM), p38 kinase inhibitor SB203850, or MEK1/2 inhibitor U0126 was added to the cells 30 min before the treatment of EGF, anisomycin, 0.7 M NaCl, or UV irradiation. The treatment of EGF and the stress conditions for inducing EGFR degradation was for 3 h. EGFR was immunoprecipitated with anti-EGFR(Mab528) and detected by immunoblotting with anti-EGFR (1005). a and c Western blot of EGFR (the top panel) and β-actin in whole cell lysates (the bottom panel) with immunoblotting. b Quantification of the immunoblotting data from three repetitions of experiments in (a). *p < 0.05, **p < 0.01, ***p < 0.001