GRB2 and neoplasm: Gas6 binds to AXL, to regulate cell survival (10–13), promote tumor cell proliferation and migration, induce epithelial mesenchymal transition (EMT), inhibit tumor cell apoptosis, and participate in tumor stem cell maintenance (14–18) by activating multiple downstream pathways including JAK/STAT3 (19), PI3K/AKT/mTOR (20), Grb2/RAS/MEK/ERK1/2 (21) and FAK/Src/NF kappa B (22).