a, Heat map with unsupervised hierarchical clustering of log(mutant/wild type (WT)) ratios from Ba/F3 cells expressing indicated mutations after drug treatment. To determine the mutant/WT ratio, half-maximal inhibitory concentration (IC50) values for each drug and cell line were calculated and then compared to the average IC50 values for Ba/F3 cells expressing wild-type EGFR (+10 ng ml−1 EGF). Squares are representative of the median of n = 3 replicates. The order of co-occurring mutations was assigned arbitrarily. Groups were assigned on the basis of structural predictions (Methods). Gen, generation. b, Dot plot of Spearman’s rho values for correlations of mutations versus exon-based group averages or structure–function-based averages for each drug. Dots are representative of rho value of each mutation; bars show mean ± s.d., n = 77 cell lines or mutations. c, Dot plot of variable importance calculated from CART. Dots are representative of variable importance for each drug; bars show median + 95% confidence interval of variable importance for all drugs (n = 18 drugs) (Supplementary Table 2). In b, c, P value was determined using a paired two-sided t-test.