Takahashi et al. [83] found that HNSCC CAF express elevated amounts of PD-L1 (also known as B7H1) and PD-L2 (B7DC); both molecules interact with PD-1 receptor on T-cells to suppress effector functions [84, 85]. The gene discussed is PDCD1LG2; the disease is head and neck squamous cell carcinoma.