PROBLEM TO BE SOLVED: To provide a novel therapeutic means for unresectable progressive recurrent colon cancer.SOLUTION: The invention relates to a therapeutic agent for colon cancer containing anti-PROK1 antibodies. The invention also provides a method for screening a substance having an anticancer action comprising measuring the expression level of PROK1 in a PROK1 expression cell under the presence and absence of a test substance, comparing with a reference cell under the absence of the test substance, and selecting the substance suppressing the expression of PROK1.COPYRIGHT: (C)2015,JPO&INPIT【課題】切除不能な進行再発大腸癌の新規治療手段を提供する。【解決手段】抗PROK1抗体を含有する大腸癌の治療剤。被験物質の存在下及び非存在下、PROK1発現細胞でのPROK1の発現量を測定し、被験物質非存在下での対照細胞と比較して、PROK1の発現を抑制した物質を選択することを含む、抗癌作用を有する物質のスクリーニング方法。【選択図】なし