Par-1 and Dia colocalize along extended regions of actin bundles, and Arp3 has a punctate cortical distribution. (A) Dia and phalloidin staining of embryos overexpressing GFP–Par-1. Before nuclear division at the embryo cortex, GFP–Par-1, Dia, and F-actin colocalize at bundles (arrows) of the broad, cap-free cortical network. At cycle 10, caps arise and GFP–Par-1, Dia, and F-actin colocalize at bundles at their apical surface (arrows) and at ingressing furrows. (B) Overexpressed Arp3-GFP puncta across the apical cap surface live. (C) Overexpressed Arp3-GFP puncta without enrichment at Dia-positive bundles (arrow) after fixation. (A–C) Images deconvolved.