Patent ID: 7332293

Claim:
A method for the identification of a substance having an ability to inhibit the transcription of a DNA coding a cell surface protein to mRNA or the expression of said cell surface protein wherein the cell surface protein has an ability to mediate the transport of an amino acid into a cell and having an ability to mediate the incorporation of at least one amino acid selected from the group consisting of leucine (Leu), isoleucine (Ile), phenylalanine (Phe), methionine (Met), tyrosine (Tyr), tryptophan (Trp), valine (Val), histidine (His) and other neutral amino acids into the cell in an Na + -independent manner, wherein the cell surface protein has an amino acid sequence selected from a) to d): a) amino acid sequence represented by SEQ ID NO:2, b) amino acid sequence represented by SEQ ID NO:4, c) amino acid sequence represented by SEQ ID NO:2, wherein 1 to 20 amino acid residue(s) is (are) substituted, deleted or added, d) amino acid sequence represented by SEQ ID NO:4, wherein 1 to 20 amino acid residue(s) is (are) substituted, deleted or added.