[1] Catholic Univ Louvain, Lab Expt Med & Endocrinol, B-3000 Louvain, Belgium
[2] Catholic Univ Louvain, Div Biochem, B-3000 Louvain, Belgium
[3] Univ Liege, Lab Tumor & Dev Biol, Liege, Belgium
[4] Univ Paris 06, Ctr Rech Biomed Cordeliers, Inst Natl Sante & Rech Med, Paris, France