GAB1 (GRB2-associated binding protein 1) is a cytoplasmic adapter protein that mediates intracellular signaling downstream of activated receptor tyrosine kinases (RTKs), including FGFR1, EGFR, insulin receptor, and MET/HGF pathways 1. GAB1 functions by recruiting signaling molecules such as Grb2 into receptor-signaling complexes 2, where it activates key downstream cascades including PI3K/AKT, ERK/MAPK, and integrin/FAK signaling 3. The protein promotes positive regulation of angiogenesis, vascular endothelial growth factor signaling, and cell migration processes [GO annotations]. In disease contexts, GAB1 overexpression drives aggressive cellular phenotypes: it promotes oral squamous cell carcinoma proliferation and invasion via the Akt/Cdh1 pathway 4, and facilitates lung adenocarcinoma cell motility through the AXL-Gab1-PI3K axis 5. Conversely, GAB1 inhibition suppresses fibroblast fibrogenesis, migration, and proliferation in skin fibrosis 3. GAB1 variants associate with asthma severity and inhaled corticosteroid responsiveness in children, with specific SNVs affecting eosinophil levels and treatment outcomes 6. These findings establish GAB1 as a critical signaling node in both normal physiological processes and pathological conditions including cancer and fibrotic diseases.