FOSL1 and neoplasm: Many colon cancers showed increased nuclear β-catenin and FRA1 expression in tumor cells located at the infiltrative tumor edge, whereas CK20 and GLUT1 were most strongly expressed in the tumor center, often close to necrotic areas, suggesting a polarity with differentiation gradients directed from the tumor edge toward the tumor center (Fig. 1a, b and Supplementary Fig. 1).