1. Department of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.
2. Departamento de Medicina Experimental, Facultad de Medicina, Universidad de Chile, Independencia 1027, Casilla 70058, Santiago 9, Chile
3. The Matilda and Terence Kennedy Institute of Rheumatology, I Aspenlea Road, Hammersmith, London W6 8LH, U.K.