Insulin is naturally produced in the human pancreas. For various reason the production is slowed or stopped causing a person to have diabetes. For many years, insulin was obtained from pigs or cows when they were butchered. Since 1978 e-coli bacteria produce insulin! The DNA sequence for insulin was taken out of a human cell and transplanted into an e-coli, thus "teaching" the bacteria to make the essential medicine for more than 20 million americans. Isn't that cool?
