FASLG and neoplasm: Tumor endothelial cells (TECs) play a key role in shielding tumor cells from immune attacks launched by the host.478 The proteins secreted by TECs trigger the polarization of macrophages towards the M2 phenotype by activating the PI3K/AKT/mTOR signaling pathway.479 Notably, TECs possess the ability to upregulate the expression of Fas ligand under the influence of various stimuli, such as a combination of IL-10, prostaglandin E2 (PGE2), and VEGF-A.