DKK1 and neoplasm: The better outcome in WNT MB has been hypothesized to be due to the secretion of a soluble Wnt antagonist like Dickkopf 1 (DKK1) or the Wnt inhibitory factor 1 (WIF1) by tumor cells, which may reduce the Wnt/β-catenin pathway activity in neighboring endothelial cells, damaging the blood–brain barrier and making the tumor more susceptible to chemotherapy [226].