FIG. 1.

Proteolytic cleavage of Rac GTPases during drug-induced apoptosis in human B lymphoma cells. (A) JLP-119 Burkitt's lymphoma cells were treated with VP-16 (8.5 μM) or staurosporine (2.0 μM) for the indicated times. Apoptosis was quantified by staining cells with Hoechst 33342 and propidium iodide and assessing nuclear morphology by fluorescence microscopy. Values are given as the percentage of total cells that are apoptotic. The results represent the means ± standard deviation from three separate experiments. (B) Extracts from the drug-treated JLP-119 cells described in the legend for panel A were subjected to Western blot immunoassay with antibodies against Rac1, Rac2, PARP, and N-Ras as described under Materials and Methods. Each lane was loaded with 20 μg of total cellular protein. Sizes are indicated to the right of the blots. The results shown are representative of three independent experiments.