Fig. 3 showed that β-catenin siRNA blocked p,p′-DDE-induced DLD1 cell proliferation as well as overexpression of c-Myc and cyclin D1. Similar to the impact of β-catenin siRNA, p,p′-DDE-induced DLD1 cell proliferation and overexpression of c-Myc and cyclin D1 were inhibited by Gli1 siRNA (Fig. 4). These results suggested both Wnt/β-catenin and Hedgehog/Gli1 signalings play important roles in p,p′-DDE-induced colorectal adenocarcinoma cell proliferation. This evidence concerns the gene CCND1 and colorectal adenocarcinoma.