Figure 5.

Endogenous securin expression is activated by β-catenin. HCT116, SW480 and DLD1 colorectal cancer cells were transfected with β-catenin-specific siRNA and control siRNA (GFP-siRNA). The effect of β-catenin knockdown on securin expression was measured by quantitative real-time RT–PCR and β-catenin expression was confirmed by Western blotting (Supplemental Figure 3). Inhibition of β-catenin expression by siRNA in colorectal cancer cells clearly reduces the endogenous securin expression. Black bars: β-catenin siRNA-transfected cells; grey bars: control cells (GFP-siRNA transfected); hatched bars: quantity of β-catenin mRNA; closed bars: quantity of securin mRNA. Quantification of securin and β-catenin-specific mRNA was done in triplicates, the amounts were normalised to the amount of β-actin mRNA, and expressed in percent relative to the control cells. The experiments were repeated twice with similar results.