[1] Univ Texas, Dept Chem, Austin, TX 78712 USA
[2] Univ Texas, Dept Biochem, Austin, TX 78712 USA
[3] Univ Calif Riverside, Riverside, CA 92521 USA
[4] Univ Calif Davis, Davis, CA 95616 USA
[5] NIH, Bethesda, MD 20892 USA
[6] Yeshiva Univ Albert Einstein Coll Med, Bronx, NY 10461 USA
[7] Case Western Reserve Univ, Sch Med, Cleveland, OH 44106 USA
[8] Imperial Canc Res Fund, Oxford OX3 9DS, England