FASLG and neoplasm: Fas ligand (FasL) and other effector molecules carried by exosomes mediate T cell apoptosis (Figure 1).15, 16, 17 Conversely, tumor-derived exosomes amplify Tregs through the transforming growth factor (TGF)-β1 and interleukin (IL)-10 pathways and increase the inhibitory activity of Tregs by upregulating FasL and other effector molecules.18