WNT4 is essential for nephrogenesis. It regulates kidney tubule induction and the mesenchymal to epithelial transformation in the cortical region. In addition, it influences the fate of the medullary stroma during development. Without it, smooth muscle α actin is markedly reduced. This occurrence causes pericyte deficiency around the vessels, leading to a defect in maturation. WNT4 probably functions by activating BMP4, a known smooth muscle differentiation factor.
