Furthermore, the protein levels of PCNA protein (a marker for cell proliferation), cyclin D1 and cyclin E (key regulators of the cell cycle), and MMP-9 (a key regulator of metastasis in colon cancer), as well as TNFα (a marker for extrinsic cell apoptosis) in nude mice were measured by IHC. This evidence concerns the gene PCNA and malignant colon neoplasm.