Fig. 5.

In a panel of ER+ BC cell lines, IC₅₀ was assessed to rapamycin and tamoxifen according to PIK3CA status. PIK3CA mutations (MCF7, T47D, KPL1) predict sensitivity to tamoxifen (A), but not rapamycin (B). Cell lines are ranked according to increasing PIK3CA-GS (C) The PIK3CA-GS could identify ER+ PIK3CA mt lines, but in the reverse direction to human BC (AUC, 0.9; P = 0.008; Fig. S1C), i.e., cell lines are associated with relatively high mTORC1 output. The rapamcyin-resistant ZR751 line was associated with the highest PIK3CA-GS value; black bars/circles represent PIK3CA mt cell lines in A, B, and C; error bars indicate 95% CI; each bar represents the mean IC₅₀ from triplicate plates.