PIK3CA and breast cancer: Phosphorylation of eIF4B at S422, S6 at S235/236, 4E-BP1 at S65 as well as the decrease in PDCD4 levels mostly depended on the PI3K/Akt/mTORC1 pathway, under any tested condition, in breast cancer cell lines in which only this pathway was up-regulated (MCF7, T47D, and MDA-MB-468) (Figure 3A, 3B and 4A).