HGF and lung carcinoma: Of patients with EGFR mutant lung cancer, 26-40% had tumors with high HGF expression and EGFR-T790M secondary mutation, 5-33% had tumors with Met gene amplification and EGFR-T790M secondary mutation, and 4-7% had tumors with high HGF expression and Met gene amplification, suggesting that dual targeting of HGF/Met and the EGFR-T790M mutation may overcome resistance to EGFR-TKIs [23,25,33].