In vivo Wnt signaling in the colon, determined by β-galactosidase expression. A) BAT-LacZ construct. B) β-Galactosidase expression by real-time PCR. Multiple vitamin depletion (MVD) increased expression by 58% in the BAT-lacZ mice (not significant) and by ∼4-fold in the BAT-LacZ×Apc1638N model (P<0.05). Data analysis was performed based on ΔCt. Data for the BAT-LacZ model is presented in a linear scale; data for the BAT-LacZ×Apc1638N model is presented in a logarithmic scale. BAT-LacZ model: n = 9 mice/group. BAT-LacZ×Apc1638N model: control, n = 10 mice; MVD, n = 11. Note that the presence of a mutant Apc allele in the hybrid, independent of diet, significantly increases β-galactosidase expression when compared with the BAT-LacZ model (P<0.01).