By finding a novel tetrahydrofolate synthetase gene and a protein encoded
by said gene, a method for identifying a compound which inhibits cell
growth accelerating activity of said protein is provided, and a judging
method, a preventing method and a treating method of colon cancer are
provided. A DNA comprising a nucleotide sequence of from the 94th to
2934th positions of the nucleotide sequence of SEQ ID NO:1 of the
SEQUENCE LISTING; a polynucleotide which specifically hybridizes with
said DNA; a protein encoded by said DNA; a recombinant vector comprising
said DNA; a transformant comprising said recombinant vector; an antibody
for said protein; a method for producing said protein; a method for
identifying a compound which inhibits cell growth accelerating activity
possessed by said protein; a method for judging colon cancer,
characterizing in that expressed amount of said DNA is measured; a kit
for judging colon cancer; a preventive agent and/or therapeutic agent for
colon cancer.