Normal mucosa adjacent to colon tumors and most of the colon cancer cells near the mucosal surface were negatively stained for CA9 (Fig. 2B-2a, 2b), whereas cancer cells located at the invasive front within deep mucosa or invading into the submucosa showed strong cell surface staining for CA9 (Fig. 2B-2c). The gene discussed is CA9; the disease is malignant colon neoplasm.