MTOR and neoplasm: Given that the PI3K‐AKT pathway has been recognized as the most aberrantly activated signaling in BC, and have been reported regulated by sEVs to promote tumor progression,29 we examined the expression of phosphorylated PI3K, AKT and mTOR in different models with immunohistochemistry, and found the higher expression in tumor tissues compared with paired in vitro models (Figure S2).