- Production and characterization of recombinant insulin-like growth factor-I (IGF-I) and potent analogues of IGF-I, with Gly or Arg substituted for Glu3, following their expression in Escherichia coli as fusion proteins. King, R., Wells, J.R., Krieg, P., Snoswell, M., Brazier, J., Bagley, C.J., Wallace, J.C., Ballard, F.J., Ross, M., Francis, G.L. J. Mol. Endocrinol. (1992)