About the Authors
Institute of Cell Biology, University of Berne, Berne, Switzerland
The authors have declared that no competing interests exist.
ABE, LS, HM, and OM conceived and designed the experiments. ABE, LS, HM, RZO, and OM performed the experiments. ABE, LS, HM, and OM analyzed the data. OM, supported by ABE and LS, wrote the paper.