1. Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
2. Rosalind Russell and Ephraim P. Engleman Arthritis Research Center, Division of Rheumatology, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA.
3. Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94143, USA.