EB1-DN and Spas change MT organization and dynamics. (A) Spas eliminated MTs in epidermal cells at the level of E-cad junctions (wild type [wt], Spas expressed in a stripe of two cells; α-tubulin, magenta; E-cad, green). (B) EB1 domains, showing MT-binding CH, coil-coiled (CC) dimerization, and acidic C terminus (Ac) are depicted, as well as new constructs with GFP and Cherry tags. (C) Sample kymographs showing growth of individual MTs in wild-type (wt) and EB1-DN cells. (D–G) EB1-DN reduced processivity of MT growth and the number of growing ends. Quantitation of individual growth event duration (D), MT growth speed (E), EB1-GFP fluorescence intensity at individual plus ends (F), and plus end density per square micrometer at the level of E-cad junctions (G). (H and I) EB1-DN changed oriented growth of MTs. (H) Projection of 20 images taken every 0.5 s. EB1-GFP, black/green; EB1-DN, magenta. (I) Quantitation of growth orientation of individual MTs in control and EB1-DN cells (Cherry-positive in H) relative to dorsal (D), ventral (V), anterior (A), and posterior (P) sides of the embryos. Red lines mark 45° segments. Bars, 5 µm. ***, P < 0.0001.