1. Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo‐ku Kyoto 606‐8502 Japan
2. Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo‐ku Kyoto 606‐8502 Japan
3. Kondoh Differentiation Signalling Project, ERATO, Japan Science and Technology Corporation, Sakyo‐ku Kyoto 606‐8305 Japan
4. Center for Molecular and Developmental Biology, Kyoto University, Sakyo‐ku Kyoto 606‐8502 Japan