Betterhumans reports on the latest in a line of studies in mice to determine the effects of regulatory proteins on muscle, fat and bone development. "A protein that blocks the production of fat in mice also gives them a bone mass four times that of normal mice, hinting at new ways of treating osteoporosis in humans. ... [It] is part of a family of 19 proteins that regulate changes that take place as embryos develop. ... Otherwise, say the researchers, there didn't appear to be any abnormal features in the bone." It is a fair way from experiments such as these to producing gene therapies for humans that address age-related degeneration - but scientists have to start with the basics.