Fig. 3

mTOR inhibitors and mitotic inhibitors cause cytostatic but not cytotoxic effects in CAL-51. a Scatter plot comparing DSS for CAL-51 computed using viability assay (CellTiterGlo) and cell death assay (CellTox Green). Some compounds caused both viability inhibition and cytotoxicity, but a large number of compounds (represented with blue stars and listed on the right-hand side of the plot) showed high degree of viability inhibition with little or no induction of cell death. b Schematic illustration of experimental workflow. c Growth curves affected by selected highlighted drugs in plot (a) showing their effect in viability inhibition is due to arrest in cell cycle rather than induction of cell death. CAL-51 cells were cultured in 96-well plates with compounds for 72 h at which point the inhibitors were either washed away or replenished (time indicated with pink arrow). Growth measured as confluency was monitored and calculated using an IncuCyte Zoom live cell microscope for 9 days. Cell growth was arrested in the presence of methotrexate, dactolisib, daporinad, AVN-944 and pictilisib; and released upon removal of the compounds. Similarly, everolimus, SNS-032 and YM155 initially arrested cell growth but eventually growth was restored, also in the presence of the compounds, pointing to a rapidly established adaptive resistance