Our immunohistochemistry indicates that well-differentiated/differentiating tumours have high levels of β-catenin in the Schwannian stroma, and it is therefore tempting to speculate that Wnt signalling may induce paracrine differentiating factors such as BMP4 and Wnt11 to prompt differentiation of neuroblast cells by Schwann cells. The gene discussed is BMP4; the disease is neoplasm.