1. From the National Laboratory of Medical Molecular Biology (Z.-G.S., W.Z., Y.-S.W., H.-Z.C., A.-B.W., H.-L.L., G.L., R.Z., J.-J.L., D.-P.L., C.-C.L.), Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China; Burnham Institute for Medical Research (Z.-G.S., W.B.S.), Cancer Center, La Jolla, Calif; and Department of Biochemistry (Z.Z.), The University of Hong Kong, China.