Figure 4.

Effect of protease inhibitors on Ft degradation after UVA irradiation of FEK4 cells. ³⁵S-labeled FEK4 cells that were pretreated overnight with the specified drug(s) were irradiated at 250 kJ/m² in the presence of inhibitors. Immediately after UVA radiation, cells were lysed and immunoprecipitated with human polyclonal Ft antibody. The drugs used were: ( A) 20 (L1) and 40 μg/ml Leupeptin (L2), 100 (Cy1) and 200 μg/ml Chymostatin (Cy2), or the combination of 40 μg/ml Leupeptin and 200 μg/ml Chymostatin (L/Cy); (B) 50 μg/ml E64-d and Calpeptin (Cal) or 1 μg/ml Pepstatin (Pep); (C) 100 μM Lactacystin (La) or MG132 (MG); (D) 50 μg/ml Chloroquine (CQ) and 30 mM ammonium chloride (AC). The irradiated samples are shown as (+). The nonirradiated controls are shown as (–). In A–D, “C” represents the controls that were not treated with drugs.