MTOR and non-small cell lung carcinoma: The PI3K/AKT/mTOR pathway is a key regulator of PD-L1 expression in NSCLC since it mediates both constitutive and inducible expression resulting from either alteration of oncogenes (e.g., EGFR, KRAS, and ALK) or extrinsic factors (e.g., IFN-γ or EGF), respectively.