Genetically engineered milk

This is cool:

A cow called Pampa Mansa could be the key to cutting the high cost of human growth hormone, which is used to treat thousands of children with growth problems. The genetically modified Jersey cow produces so much of the hormone in her milk that just 15 cows like her could meet the current world demand.

Human growth hormone once had to be extracted from human cadavers but is now made in genetically modified bacteria. This form of the hormone is safer, but treatments can cost $30,000 a year.

To create an alternative source, a team led by Daniel Salamone at the University of Buenos Aires in Argentina added the human gene to cow cells growing in a dish. Pampa Mansa was created by cloning one of the modified cells.

At the age of one, Pampa Mansa was already producing 5 grams of the hormone per litre of milk, 10 per cent of the milk's protein content. That translates into at least 4 kilograms a year, over four times as much as a typical bacterial fermenter, the team will tell a meeting of the International Embryo Transfer Society in Copenhagen next week.

Someone is currently trying to do the same with spider silk, one of the strongest materials by weight known to man (5 times stronger than steel, twice as elastic as nylon, and biodegradable too). (Amusingly enough, you can't farm spiders the way you can silkworms, because the spiders eat each other.)

I wonder if anyone has tried doing this with insulin? I remember reading that the drive to produce recombinant human insulin in E. coli was the impetus behind the start of the "molecular biology revolution" in the late 1970's, and yet when they actually figured it out, it wasn't a whole lot cheaper than harvesting pig pancreases.