PIK3CA and breast cancer: While BEZ235 was mainly used, Serra et al. [61] also demonstrated ERK activation in response to a diverse range of agents such as pan-PI3K inhibitor (GDC-0941), p110α inhibitor (PIK-90), AKT inhibitor (MK-2206), as well as mTOR inhibitors (RAD001 and Torin1) in a couple of HER2+ BC cell lines including BT474, suggesting ERK activation is a broad consequence of PI3K signalling inhibition regardless of the targeted node[61].