DN Itgβ1 overexpression affects the protrusive activity of AV ECs. (A) Domain organization of the control Tg(UAS:mCherry) and the DN Itgβ1 Tg(UAS:mCherry-itgb1^DN transgenes. SP, signal peptide; TM, transmembrane; ICD, intracellular domain. (B–G) Representative images and schematics of the control (B–D) and DN Itgβ1–overexpressing (E–G) AV ECs at 56 and 75 hpf. (H and I) Proportions of cells expressing mCherry-tagged control or DN Itgβ1 in total AV ECs (H; control, n = 242 cells/12 embryos; DN Itgβ1, n = 361 cells/26 embryos) or leader AV ECs (I; control, n = 31 cells/12 embryos; DN Itgβ1, n = 36 cells/26 embryos). Whereas 100% of leader ECs expressed the control transgene, only 24% expressed DN Itgβ1 (P = 2.03^e−9). (J) Number of leader ECs in control (n = 12 embryos) and DN Itgβ1–overexpressing (n = 26 embryos) animals. The number of leader ECs in the superior and inferior AVC was significantly reduced when DN Itgβ1 was overexpressed (averages of 2.58 and 1.38 cells per embryo in control and DN Itgβ1, respectively; P = 4.5^e−4). An unpaired Student’s t test was used for I and J. Error bars represent standard deviation; asterisks indicate statistical significance. Scale bars: 20 µm.