Movie 1.

Timelapse imaging of H2B-Cerulean (blue) and iGata6-mCherry expression (red) in wild-type and Med12-mutant cells during Epi and PrE differentiation under same conditions as in Fig. 3E. Following time lapse imaging, cells were immunostained for the Epi-marker NANOG (green) and the PrE marker SOX17 (magenta). Nuclei in immunostainings labelled with Hoechst dye (cyan). Scale bar: 50 μm.