FIG. 4.

MMS-induced apoptosis can be inhibited by neutralizing CD95-L antibodies. (A) Wild-type and c-jun^−/− cells were left untreated (Co) or were treated with 300 μM MMS in the presence or absence of a neutralizing anti–mouse CD95-L antibody (30 μg of MFL3 per ml) (anti CD95-L). Apoptosis was detected by microscopy. Very similar results were obtained with a neutralizing anti–human CD95-L antibody (NOK-1). (B) Wild-type and c-jun^−/− cells were left untreated (Co) or were treated with 200 μM MMS in the presence (□) or absence (■) of a neutralizing CD95-L antibody (30 μg of NOK-1 per ml). Apoptosis was measured by annexin V staining and flow cytometry. A representative of three experiments with similar outcomes is shown. The standard deviation was less than 10%. When we calculated the percentage of specific apoptosis according to the formula 100 × [(percent experimental apoptosis − percent spontaneous apoptosis in the control/(100 − percent spontaneous apoptosis in the control)], MMS-induced apoptosis in wild-type cells in the absence and presence of the neutralizing antibody was 38 and 18%, respectively.