Susceptibility of 32 D-neo (□), 32D-max (○), and 32D-c-myc (◊) cells to six different antineoplastic agents in the presence of IL-3. Cells of >95% viability were plated in the presence of IL-3 and the indicated concentrations of drug as described in Materials and Methods. At various times thereafter, viability was determined by trypan blue staining of a 40-μL aliquot. The results shown here depict survival curves at 40 hours for ADR; 41 hours for CDDP, CPT, and N-Mus; 16 hours for Taxol; and 48 hours for VP-16. Each graph is representative of three or more experiments (±1 SE. The percent values shown have been normalized to those of cells grown in the absence of any drug for the equivalent length of time. The inserts show the results of electrophoresis of apoptotic DNAs from cells grown in the highest concentration of each drug for the times indicated above. All inserts show DNAs from 32D-neo, 32D-max cells, and 32D-c-myc (left to right).