Figure 3. Robo4 siRNA specifically knocks down Robo4 mRNA and protein level. A:Robo4 expression in RF/6A and human RPE cells was significantly knocked down at the mRNA level, measured by real-time RT–PCR 48 h after transfection. B: The protein expression of Robo4 protein in RF/6A and human RPE cells was measured by immunoblotting, normalized to β-actin expression in RF/6A and RPE cells. One was a representative photograph of the western-blot analysis of Robo4 expression in RF/6A; 2 was a representative photograph of the western-blot analysis of Robo4 expression in RPE; 3 was the data of the relative Robo4 protein in the NS, UT and Robo4 siRNA-treated cells. Values are the means±SD of at least three independent experiments. Abbreviations: control siRNA treated cells (NS); untransfected cells (UT); Robo4 siRNA-treated cells (Robo4 siRNA). Asterisks denote values signigicantly different from Robo4 siRNA-treated group compared to NS and UT group (p<0.01). The pixel intensity of NS was set to 100%.