FAS and neoplasm: CAFs have been shown to abrogate CD8+ T-cell function by restricting CTL recruitment to tumor tissues44,54, producing aberrant ECM deposition to function as a physical barrier against tumor infiltration of CTLs15, and driving antigen-mediated AICD of tumor-specific CTLs present within the tumor milieu by the apoptosis induction of CD8+ T cells via Fas (expressed in CD8+ T cells) and FasL (expressed in CAFs) pathway, as well as CD8+ T-cell anergy via PD-1 (expressed in CD8+ T cells) and PD-L2 (expressed in CAFs) pathway19.