Skip to main content
. 2008 Nov 28;4(11):e1000287. doi: 10.1371/journal.pgen.1000287

Figure 2. Drug response is correlated across multiple drugs, to growth rate and to baseline ATP levels of the cell line.

Figure 2

(A) Relative drug responses were calculated for each individual as described in Methods to obtain a single number summary of the cell line response to each drug on each day. The black circles represent an individual cell line's relative response to 6MP assayed on day one plotted against 6MP relative response assayed on day two. The red circles similarly represent relative response to 6MP plotted against relative response to MTX, both assayed on day one. The green circles represent relative response to 6MP plotted against relative response to 5FU, again both assayed on day one. Lines represent regressions for each of the three comparisons and show that not only is relative drug response a reproducible trait, but also can be correlated across multiple drugs. (B) Using online data made publicly available by Watters et al. [25], relative drug response to docetaxel and 5FU was calculated using the 427 individuals with no missing data to obtain a single number for each drug, in each individual, as in (A). Response to docetaxel was plotted against 5FU for each individual. The line represents the regression for the comparison and indicates that the effect observed in (A) is neither limited to our experiments, nor to the particular drugs we attempted. (C) The baseline growth-rate of each individual's cell line was estimated as described in the Methods. This growth rate is plotted against relative response for 6MP (black), MTX (red), and 5FU (green). Lines represent regressions for the respective comparisons and all correspond to significant correlations. (D) For each individual, baseline ATP levels were measured using Celltiter glo in the mock-treated wells in drug response assays. EC50 response was calculated correcting for growth rate (see Methods). Relative ATP levels were plotted against the growth-rate corrected EC50 for MTX (red), and 5FU (green). Lines represent regression for the comparisons and indicate significant correlations.