1 University of Copenhagen, Department of Biology, Section for Cell Biology and Physiology, Universitetsparken 13, DK-2100 Copenhagen, Denmark. Electronic address: jacob.hansen@bio.ku.dk.
2 University of Copenhagen, Department of Biology, Section for Cell Biology and Physiology, Universitetsparken 13, DK-2100 Copenhagen, Denmark. Electronic address: inovak@bio.ku.dk.