Order of authorship in the original paper: Itakura, Hirose, Crea..., Bolivar, Boyer. Synthesis of the gene for somatostatin (growth hormone-inhibiting hormone (GHIH). This was the first demonstration of a foreign gene inserted into E. coli and the first hormone genetically engineered in bacteria. The technique led to the biotechnological production of insulin by Genentech under the product name, Humulin. 

(Thanks to Juan Weiss for this reference and its interpretation).

Working at Genentech, Kleid and Goeddel and colleagues were the first scientists to apply genetic engineering techniques, incorporating chemically synthesized DNA encoding human insulin into E. coli, that expressed, after appropriate treatment, synethetic human insulin. Digital facsimile from PubMedCentral at this link.