Inserm, U1054, Montpellier, France.|Inserm, U1054, Montpellier, France.|Inserm, U1054, Montpellier, France.|Department of Cell and Developmental Biology, Weill Cornell Medical College of Cornell University, New York, NY, USA.|Inserm, U1004, Villejuif, France.|Inserm, U1054, Montpellier, France.|Inserm, U1054, Montpellier, France. pem@cbs.cnrs.fr.