About the Authors
Center for Developmental Genetics, Department of Biology, New York University, New York, New York, United States of America
The authors have declared that no competing interests exist.
EOM, AC, MFW, and CD conceived and designed the experiments. EOM, AC, MFW, and DV performed and analyzed the experiments. RJJ and TAC contributed reagents. TAC and FP made the initial observations. EOM, AC, and CD wrote the paper.