FASLG and neoplasm: Secondly, similar to tumor cells, the induced TAMs can express Fas-L and release active soluble Fas-L to induce apoptosis of Fas+ lymphocyte [171], while CAFs can up-regulate Fas-L and PD-L2 through MHC-1 antigen cross-presentation and inhibit the activity of CD8+ T cells [170], thus forming a TME lacking lymphocyte infiltration.