1. From the Departments of Biological Chemistry (Á.B., R.L., P. Tarr, M.M.W., P.A.E.), Medicine (Á.B., R.L., P. Tontonoz, R.K.T., J.F., P.A.E.), Pathology and Laboratory Medicine (L.P., P.T.), the Howard Hughes Medical Institute (P. Tontonoz) and the Molecular Biology Institute (P.A.E., P. Tontonoz), UCLA, Los Angeles, Calif; Department of Cellular and Molecular Medicine (A.C.L.), UCSD, La Jolla, Calif.