Patent ID: 8124052

Claim:
A method of identifying a nucleic acid encoding a targeting domain associated with liver metastasis, the method comprising: (a) injecting into a subject a library of phage displaying a collection of polypeptides expressed from nucleic acids that are greater than 100 nucleotides in length and that are derived from a eukaryotic cell, wherein each polypeptide is expressed from the library of phage at a copy number of about 0.1 copy to about 1 copy per phage; (b) collecting from the subject's liver phage that, based on the displayed polypeptide, target to and are retained by the liver; (c) repeating steps (a) and (b) with phage collected in (b) for one or more cycles; and (d) identifying from phage collected in (b) one or more nucleic acids encoding a targeting domain that is associated with liver metastasis, wherein, if the phage does not display a polypeptide, it exhibits low relative retention by the liver.