ACTA1 and neoplasm: The scaffold-free edge retains the original tumour architecture showing the characteristic reverse bilayer phenotype of Wnt1 tumours where basal cells, defined by their expression of cytokeratin-14 (CK14), α-smooth muscle actin (αSMA) and nuclear p63, line the lumen35,36 (Fig. 2a,i-iii, lumen marked as*).