Figure 2. High glucose negatively regulates Wnt/β-catenin signaling. (A) C2C12 cells were incubated for 24 hours in the presence or absence of Wnt3a (50 ng/mL) or high glucose (100 mM), followed by quantitative reverse transcription-polymerase chain reaction of osteogenic marker genes. (B) MLO-Y4 cells were transiently transfected with the β-catenin expression vector and Top-Flash luciferase reporter and cultured in the presence or absence of Wnt3a or high glucose (40 mM) for 72 hours. The graphs indicate the mean±standard deviation of (A) the triplicate or (B) quadruplicate samples (^a)P<0.05, ^c)P<0.001, ^d)P<0.0001). In the figures, 5 and 100 mM indicate the concentration of glucose in the culture medium.