Transcriptional activation of the Wnt pathway in MTX-resistant cells leads to DKK1 overexpression. HT29 cells, either sensitive or resistant, were transiently transfected with 1 μg of a luciferase reporter of β-catenin-mediated transcriptional activation (TOPFLASH) using Fugene™ HD in the presence or absence of 2 μg of E-cadherin expression vector (pBATEM2-CDH). Thirty hours after transfection, luciferase activity (relative light units (RLU)) was assayed. The protein content was used to normalize the luciferase activity for each sample and is expressed relative to that of pGL3 basic vector (mean ± standard error of the mean for triplicate wells). *P < 0.05.