Mitotic spindles in Myo10 morphants undergo spindle pole fragmentation, and Myo10 interacts with the spindle assembly factor TPX2. (a) Stills taken from a confocal video (Video 1) of mitosis in a control embryo using GFP–α-tubulin to visualize the spindle; time stamps indicate time in minutes and seconds. (b) Stills taken from a video of a Myo10 morphant spindle (Video 4) showing that it assembles in a bipolar fashion, but, subsequently, a pole fragments to form a supernumerary pole (arrows). (c) Confocal micrographs of mitotic spindles in Myo10 morphants immunostained for α-tubulin (red) and γ-tubulin (green). All supernumerary poles in the multipolar spindles possess γ-tubulin, independent of whether the poles have just arisen (top, arrows) or are more established (bottom, arrows). (d) Mitotic spindles in water-injected and Myo10 morphant embryos immunostained for α-tubulin (red) and TPX2 (green). TPX2 localization is diffuse in the Myo10 morphant compared with the more focused pole localization in controls. (e) Western blot of GST pull-down assay showing that full-length TPX2 pulls down with GST-Myo10-MyTH4/FERM (GST-Myo10-M/F) but not GST alone.