[1] Univ Modena & Reggio Emilia, Dept Biomed Sci, Modena, Italy
[2] Univ Barcelona, Dept Biochem & Mol Biol, E-08007 Barcelona, Spain
[3] Natl Inst Drug Abuse, DHHS, NIH, Intramural Res Program, Baltimore, MD USA
[4] Karolinska Inst, Dept Neurosci, Div Cellular & Mol Neurochem, Stockholm, Sweden