Disclosed is a means for preventing or treating cancer through the regulation of the expression or function of a target molecule that is different from those utilized in conventional techniques, as a novel means to be used in a molecule targeting therapy for cancer. Also disclosed is a means for screening a substance having a prophylactic or therapeutic activity on cancer using the target molecule. Specifically disclosed is a cell adhesion inhibitor for a cancer cell, which comprises an antibody directed against a protein comprising an amino acid sequence that is identical or substantially identical to the amino acid sequence depicted in SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6 or a partial peptide of the protein. Also disclosed is a cell adhesion inhibitor for a cancer cell, which comprises an antisense polynucleotide comprising a nucleotide sequence or a part thereof, wherein the nucleotide sequence is complementary or substantially complementary to a nucleotide sequence for a polynucleotide encoding a protein comprising an amino acid sequence that is identical or substantially identical to the amino acid sequence depicted in SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6. Further disclosed is a cell adhesion inhibitor for a cancer cell, which comprises a substance capable of inhibiting the expression and/or activity of a protein comprising an amino acid sequence that is identical or substantially identical to the amino acid sequence depicted in SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6
