Fig. 2.

Conserved and divergent drug interactions between cell types. A comparison of α scores in two yeast species. Based on the 95% confidence interval of self–self interactions, interaction scores are interpreted as follows: α < −0.8 as synergistic, α > + 0.8 as antagonistic. Additive drug combinations are within the magenta shaded area on the y-axis for S. cerevisiae and within the green shaded area on the x-axis for C. albicans. Self–self drug pairs are marked in blue and are centered on zero for both axes, as expected. α scores in C. albicans and S. cerevisiae significantly correlate, showing that drug interactions are conserved between these two distantly related yeast species (Spearman correlation test r = 0.42, p-value = 1.8 × 10⁻⁴). However, not all drug pairs followed this trend. At the upper left and lower right quadrants are highly divergent drug pairs, showing positive interactions in one species and negative interactions in the other