PIK3CA and small cell lung carcinoma: Likewise, c-MET is another important TKR in SCLC; when activated by its ligand, hepatocyte growth factor/scatter factor (HGF/SF) is indeed able to modulate downstream molecules such as growth factor receptor protein 2 (Grb2), the p85 subunit of PI3K, STAT3 and Grb2 Associated Binder-1 (Gab1), leading to proliferation, survival, motility, invasion of the extracellular matrix and tubules formation.