To investigate if the WNT5A-mediated inhibition of β-catenin is mediated through altered ERK1/2 signaling, we next treated the breast cancer cell lines with U0126, a highly selective inhibitor of both MEK1 and MEK2 resulting in impaired ERK signaling (Supplementary Figure 4A and 4B). The gene discussed is MAP2K1; the disease is breast carcinoma.