Researchers at the Dana-Farber Cancer Institute have been able to identify proteins that were released from muscles during exercise in relatively small quantities. Using their method, the team was able to demonstrate that the neurotrophic factor prosaposin was produced during exercise. Prosaposin is “a well-known CNS neurotrophic factor, but has never been seen to come out of muscle or fat,” Bruce Spiegelman told BioWorld. Spiegelman is a researcher at the Dana-Farber Cancer Institute and Stanley J. Korsmeyer Professor of Cell Biology and Medicine at Harvard Medical School.