1. From Signal Transduction Laboratory (E.V., L.W., C.W., N.A., M.A.V., P.X.), Hanson Institute, Institute of Medical and Veterinary Science (C.H., J.R.G.), and Department of Medicine, University of Adelaide (J.R.G., M.A.V., P.X.), Australia; and Department of Medicine (V.K.K.C.), University of Cambridge, UK.