Figure 1.

Identification of KIF13B domains inhibiting the interaction of KIF13B with vascular endothelial growth factor receptor 2 (VEGFR2). A: Schematic of the domains of KIF13B and truncated domains used in the study. B: For the in vitro binding assay, the domains of KIF13B [domains of unknown function (DUFs) 2A, 2B, and 2C] were expressed in bacteria and tested for binding to VEGFR2 in human primary umbilical vein endothelial cell (HUVEC) lysates by the pull-down assay. VEGFR2 was detected by Western blotting using an antibody. C:In vitro two-dimensional capillary network formation of HUVECs treated with either control virus (FLAG vector) or virus encoding truncated mutants of FLAG-KIF13B in Matrigel supplemented with VEGF (2.2 nmol/L). D and E: Vascular endothelial growth factor (VEGF)– and sphingosine-1-phosphate (S1P)–induced invasion in three-dimensional collagen matrices. HUVECs were infected without virus or with control versus FLAG-DUF2C or FLAG-DUF2 for 2 days and tested for invasion into collagen in the presence of S1P or VEGF (2.2 nmol/L). Results are representative of three individual experiments. Quantification of the collagen invasion assay is given in D by measuring distance of invading endothelial cells. Data are expressed as means ± SEM (C and D). n = 15 and 9 (C); n = 50 sprouts (D). ^∗P < 0.05. Scale bars: 200 μm(C); 100 μm (D). aa, amino acid; Cap-Gly, cytoskeleton-associated protein glycine-rich; FHA, forkhead associated; GST, glutathione S transferase; MBS, membrane-associated guanylate kinase–binding stalk; pro, proline rich; S, oligopeptide derived from RNase A (alias S-tag).