Figure 4.

Normal and tumor cells are equally sensitive to continuous CDK1 inhibition. (a) Clonogenic survival assay of tumor and normal cells treated for 20 h or continuously with increasing concentration of RO-3306. Cultures were grown for three days to 80% confluence, lifted and seeded as single cells. RO-3306 was added 3 h after seeding and either removed after 20 h or left for the duration of the experiment. Colonies were stained after 12 days. Representative of three independent experiments, data is presented as mean +/- SD from triplicate wells. (b) Comparison of IC50 values for tumor and normal cells. IC50 values were determined for each cell line using the data in panel A. Mean IC50 was calculated for both tumor and normal cells grouped together. Statistical differences were confirmed by t-tests, ** p < 0.01.