HGF and non-small cell lung carcinoma: Peng et al. studied EGFR-TKI-resistant NSCLC cells with c-MET amplification, HGF, and EGFR-T790M, three known resistance mechanisms, and found that HGF, MET amplification, and EGFR-T790M upregulate the expression of programmed cell death ligand 1 (PD-L1) in NSCLC and assist tumor cells in immune evasion through different mechanisms [58].