HGF and cancer: Due to a better understanding of the ligand, the receptor, and activators, many HGF and Met inhibitors have been developed (inhibitors for HGF activators, HGF inhibitors, Met antagonists, and mainly Met kinase inhibitors) and some are being tested in clinical trials for cancer therapy (Luraghi et al., 2012; Maroun and Rowlands, 2014; Zhang et al., 2018).