Figure 3. mTOR kinase inhibitors show the highest extent of synergy in combination with lapatinib.

A. SkBr3 cells were treated with increasing concentrations of lapatinib and the indicated second drugs at an equimolar drug ratio in a matrix format for 72 hours and the combination indices were calculated. The CI is plotted against effective dose values that resulted in 50%, 75% and 90% effects on viability. B. The CI is plotted against a continuous range of fraction affected (Fa) values. CI < 0.9 synergy, CI > 1.1 = antagonism and CI 1 = additivity.