TCF7 and melanoma: The activation of Wnt signaling resulted in increased luciferase activity only for the full length but not for the ΔβCat-TCF7 construct (Fig. 5e, Supplementary Fig. 6a) and this was phenocopied in the melanoma Mel888 cell line, where β-catenin is constitutively active due to a S37F mutation31 (Fig. 5f).