In 1978, U.S. scientists announced the production of human-type insulin by a strain of E. coli bacteria, that had been genetically engineered after months of creative use of gene-splicing techniques. The work was a joint effort by research teams in California at the biochemical firm, Genentech Inc, San Francisco and the City of Hope National Medical Center, Los Angeles. A normal body's production of insulin takes place within cells of the pancreas, programmed by certain genes (segments of DNA). The scientists synthesized copies of these genes and inserted them into a weakened lab strain of the intestinal microbe Escherichia coli. In 1982, insulin was the first recombinant DNA drug to be marketed, Humulin by Eli Lilly & Co.«[Image: graphic suggesting recombinant DNA cell culture.]