[1] Univ Freiburg, Inst Anat & Cell Biol, Dept Mol Embryol, D-79104 Freiburg, Germany
[2] Univ Tokyo, Grad Sch Med, Dept Mol Pathol, Tokyo 1130033, Japan
[3] Leiden Univ, Med Ctr, Dept Mol Cell Biol, NL-2300 RC Leiden, Netherlands
[4] Leiden Univ, Med Ctr, Ctr Biomed Genet, NL-2300 RC Leiden, Netherlands