We reported in a HNSCC mouse model that an increase in programmed death-ligand 1 (PD-L1) expression can be elicited by Pten gene deletion [116], suggesting PI3K/mTOR pathway activation contributes to PD-L1/PD1 stimulation in HNSCC. The gene discussed is PIK3CG; the disease is head and neck squamous cell carcinoma.