TGFB1 and neoplasm: Specifically, we propose that TGF-β inhibits Wnt/β-catenin signalling through the regulation of Wnt5a expression and that alteration in TGF-β signalling via dominant-negative interference or Wnt5a signalling, using Wnt5a-/- mammary tissue, promote the stability of intracellular β-catenin and redirect the formation of tumours to a Wnt/β-catenin phenotype.