Behind Paywall; Didn't Read.
http://www.ncbi.nlm.nih.gov/pubmed/8425216
http://www.nature.com/nature/journal/v221/n5183/pdf/221838a0.pdf
http://www.nature.com/nature/journal/v373/n6516/pdf/373663b0.pdf
http://www.nature.com/nbt/journal/v15/n10/pdf/nbt1097-961.pdf
http://www.sciencemag.org/content/273/5280/1392.full.pdf