[1] Univ Texas Austin, Inst Cellular & Mol Biol, Austin, TX 78712 USA
[2] Univ Texas Austin, Dept Mol Biosci, Austin, TX 78712 USA
[3] Univ Toulouse 3, Univ Toulouse, Lab Biol Cellulaire & Mol Controle Proliferat, F-31062 Toulouse, France
[4] CNRS, Lab Biol Cellulaire & Mol Controle Proliferat, F-31062 Toulouse, France
[5] Univ Texas Austin, Dept Chem, Austin, TX 78712 USA