Figure 10. Effect of Robo4 on the tube formation of RF/6A cells. Untransfected cells (A), NS siRNA-treated cells (B) and Robo4 siRNA-treated cells (C) were plated on Matrigel as described in Methods. After 24 h of incubation, UT and NS group cells formed well organized capillary-like structures (A, B), while Robo4 siRNA group cells ability to organize was severely compromised (C). Values are the means±SD of at least three independent experiments. Asterisks denote values significantly different from those of cells treated with Robo4 siRNA compared to NS siRNA and UT group (D, p<0.01). Abbreviations: untransfected cells (UT); control siRNA-treated cells (NS); Robo4 siRNA-treated cells (Robo4 siRNA) . The number of UT group was set to 100%.