Laura C. Kim1,2,3, Nicholas P. Lesner1,2,3 and M. Celeste Simon1,2 1Abramson Family Cancer Research Institute, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA 2Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA Correspondence: celeste2{at}pennmedicine.upenn.edu ↵3 These authors contributed equally to this work.