PROMOTION OF CANCER CELL MIGRATION: AN INSULIN-LIKE GROWTH FACTOR (IGF)-INDEPENDENT ACTION OF IGF-BINDING PROTEIN-6

A family of six high-affinity IGF binding proteins (IGFBPs 1-6) plays an important role in modulating IGF activities. Recent studies suggest that some IGFBPs may have IGF-independent effects, including induction of apoptosis and modulation of cell migration. However, very is about possible IGF-independent actions of IGFBP-6. mutant for acid residues (Pro 94 97 98 ) in its N-domain IGF-binding site. A >10,000-fold loss of binding affinity for IGF-I and IGF-II was observed using charcoal solution binding assay, BIAcore biosensor and ligand blotting.