1. Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), 27100 Pavia, Italy
2. International Centre for Genetic Engineering and Biotechnology, 34012 Trieste, Italy
3. Department of Public Health and Cell Biology, University of Rome Tor Vergata, 00133 Rome, Italy
4. Laboratory of Neuroembryology, Fondazione Santa Lucia, 00143 Rome, Italy