Flahaut et al. and Bourguignon et al. have shown that the Wnt/β-catenin pathway is important in ABCB1 regulation in colorectal cancer, neuroblastoma, and breast cancer (Flahaut et al., 2009[7]; Bourguignon et al., 2009[2]). The gene discussed is ABCB1; the disease is breast carcinoma.