NODAL and malignant colon neoplasm: Immunohistochemistry displayed that NODAL was expressed at a higher level in human colon cancer tissues than in adjacent noncancerous colon tissues (Figure 3(b)), as evidenced by our observations that 90% of cells in colon cancerous glandular tissues were positive for NODAL (Figure 3(a)), whereas only 30% of cells in colon noncancerous glandular tissues were stained positively for NODAL (Figure 3(b)).