Fig. 4. Dronc processing is required for apoptosis in S2 cells. (A) S2 cells were transfected with plasmids expressing wild-type Dronc or the indicated Dronc mutants. Wild-type Dronc was also transfected into Dark-RNAi-treated cells. Cell lysates were immunoblotted with anti-Dronc antiserum. The single asterisk represents the Dronc cleavage product resulting from cleavage at D113 and E352, whereas the double asterisk represents a non-specific band detected by the antiserum. L, Dronc large subunit. (B) S2 cells were co-transfected with various Dronc constructs and a plasmid expressing eGFP. At 48 hours after transfection, eGFP-positive cells were counted and this number compared with the number of surviving cells co-transfected with CAT and eGFP (set at 100%).