[1] CALTECH, DIV BIOL, PASADENA, CA 91125 USA
[2] HARVARD UNIV, INST CELLULAR & DEV BIOL, CAMBRIDGE, MA 02138 USA
[3] UNIV PARIS 07, F-75221 PARIS 05, FRANCE
[4] INSERM, F-75005 PARIS, FRANCE
[5] UNIV ARKANSAS MED SCI, DIV GERONTOL RES, LITTLE ROCK, AR 72205 USA
[6] FAC MED STRASBOURG, CNRS, LGME, F-67000 STRASBOURG, FRANCE
[7] STANFORD UNIV, MED CTR, DEPT BIOCHEM, STANFORD, CA 94305 USA
[8] UNIV PENN, DEPT BIOL, PHILADELPHIA, PA 19104 USA
[9] CNRS, INST JACQUES MONOD, PARIS 05, FRANCE