Hepatocyte growth factor (HGF) is a potent mitogen and pleiotropic growth factor with broad tissue distribution and signaling capacity 1. Structurally, HGF is a disulfide-linked heterodimer derived from a 728-amino acid precursor, composed of a 69 kDa alpha-subunit containing four kringle domains and a 34 kDa beta-subunit 1. Functionally, HGF acts as a primary ligand for the MET receptor tyrosine kinase, binding with high affinity (Kd 20-30 pM) and promoting receptor dimerization to activate downstream MAPK and PI3K/AKT signaling cascades 1. Beyond hepatic regeneration, HGF regulates diverse physiological processes including hair growth through dermal adipocyte secretion, promoting hair matrix keratinocyte proliferation and pigmentation via Wnt/β-catenin activation 2. Pathologically, HGF/MET signaling drives tumor progression across multiple cancer types. In gastric cancer, HGF/c-Met activation creates a feedback loop with Notch1 signaling promoting proliferation and migration 3. In melanoma, HGF upregulates integrins through USP22-mediated stabilization of the Sp1 transcription factor, facilitating metastasis 4. In breast cancer, HGF cooperates with CCL2/CCR2 signaling to enhance growth, invasion, and metabolic reprogramming 5. These findings establish HGF as a critical regulator of both tissue homeostasis and pathological processes, with implications for therapeutic targeting in cancer and regenerative medicine.