Researchers from the Tufts University School of Engineering and  collaborators from MIT  have now engineered E. coli bacteria to produce large quantities of a critical compound that is a precursor to the cancer drug Taxol, originally isolated from the bark of the Pacific yew tree. The tree's bacteria can produce 1,000 times more of the precursor, known as taxadiene, than any other engineered microbial strain.

This would bring down the cost of taxol, which is used as anticancer drug against lung, ovarian and breast cancer

Source:
http://www.healthcanal.com/cancers/11266-Researchers-Engineer-Microbes-for-Low-Cost-Production-Anticancer-Drug-Taxol.html