FAS and osteosarcoma: In the case of oral-, colon-carcinoma cells and B lymphoblastic cell line (47) and osteosarcoma (48), γδ T cells exerted this cytotoxicity mainly via TCRγδ- and Fas-/perforin-mediated mechanisms, or by blocking PD-1 signal after VPA and Zol treatment (with a minor role of NKG2D and TRAIL), respectively.