<p>It is intended to provide a colon cancer metastasis inhibitor and a method of inhibiting colon cancer metastasis characterized by inhibiting the function of a protein Asef capable of binding to the gene product of a tumor suppressor gene APC which plays an important role in tumorigenesis and tumor development process (i.e., the activity of binding to APC gene product or the guanine nucleotide exchanger activity) and/or inhibiting the expression of Asef gene.</p>
