ACKNOWLEDGMENT We thank William Lowe Jr., Alfred Rademaker, Evan Osmundson, Finola Moore and Yiran Zhou for their scientific advices, and Thomas O'Grady, Brian Zwecker, Alba Santana and Suchitra Prasad for their excellent technical assistance. This work was supported by funds from the National Institute of Health (R01-HD38085, CA100204, and CA112282 to H.K. and DK066044 to M.P.G.), Lynn Sage Cancer Research Foundation, Phi Beta Psi Sorority, Searle Leadership Fund, Zell Fund, H. Foundation, the Director Fund of Robert H. Lurie Comprehensive Cancer Center, and the Department of Molecular Pharmacology and Biological Chemistry. CONFLICT OF INTEREST The authors declare no conflict of interest.