Affiliation: | (1) Department of Bacteriology, Karolinska Institute, Box 60400, S-104 01 Stockholm, Sweden;(2) Department of Microbiology, University of Lund, Sölvegatan 21, S-223 62 Lund, Sweden;(3) Present address: Department of Cellular and Developmental Biology, The Biological Laboratories, Harvard University, 02138 Cambridge, MA, USA;(4) Present address: Ludwig Institute for Cancer Research, Karolinska Institute, Sweden |