1. Research Group ‘Clonal Variability’, Division of Cell‐ and Immune Biology, GBF – German Research Centre for Biotechnology, Mascheroder Weg 1, D‐38124 Braunschweig, Germany.
2. Klinische Forschergruppe OE6711, Medizinische Hochschule Hannover, Carl‐Neuberg‐Strasse 1, D‐30625 Hannover, Germany.
3. Microbiology and Tumor Biology Center, Karolinska Institutet, SE‐17177 Stockholm, Sweden