As expected for SW1222-derived xenografts, nuclear β-catenin and FRA1 marked tumor cells predominantly at the leading tumor edge, while CK20 and GLUT1 marked cells close to the necrotic tumor center within these clones, indicating clonal axis formation along the polarity of the centripetal differentiation axis in these tumors (Fig. 3d). The gene discussed is SLC2A1; the disease is neoplasm.