Affiliation: | (1) Laboratory for Cytochemistry and Cytometry, Department of Molecular Cell Biology, Leiden University Medical Centre, Wassenaarseweg 72, NL-2333 AL Leiden, e-mail: A.K.Raap@MCB.MedFac.LeidenUniv.NL Tel.: +31-71-5276187, Fax: +31-71-5276180, |