PECAM1 and neoplasm: Phospho–flow cytometry analysis revealed that low-dose RAD001 treatment inhibited p-S6, a downstream target of mTORC1 signaling, in CD31+ ECs (Figure 1C), but not in CD45–CD31– populations (including tumor cells) and CD45+ immune cells (Figure 1D), suggesting that low doses of RAD001 primarily target ECs within the tumor microenvironment.