- The heparin binding domain of vitronectin is the region that is required to enhance insulin-like growth factor-I signaling. Maile, L.A., Busby, W.H., Sitko, K., Capps, B.E., Sergent, T., Badley-Clarke, J., Ling, Y., Clemmons, D.R. Mol. Endocrinol. (2006)









