[1] Univ Roma La Sapienza, Dept Cellular Biotechnol & Hematol, I-00161 Rome, Italy
[2] Pasteur Inst Fdn Cenci Bolognetti, I-00161 Rome, Italy
[3] Univ Bologna, Dept Expt Pathol, I-40126 Bologna, Italy
[4] Univ Konstanz, Dept Biol, Mol Toxicol Grp, D-78457 Constance, Germany