Patent ID: 7727761

Claim:
A method of stimulating the activity of Flt4 receptor tyrosine kinase (Flt4) in Flt4-expressing cells, comprising the steps of: (a) preparing a polynucleotide comprising a nucleotide sequence that encodes a polypeptide that binds to the extracellular domain of human Flt4, wherein the polypeptide has an amino acid sequence comprising a continuous portion of the amino acid sequence shown in SEQ ID NO: 8 effective to permit said binding; (b) transforming or transfecting a cell with the polynucleotide that is operably linked to an expression control sequence such that the cell expresses and secretes a polypeptide encoded by said polynucleotide, wherein said secreted polypeptide binds the extracellular domain of human Flt4 and has a molecular weight of about 23 kD as assessed by SDS-PAGE under reducing conditions; and (c) contacting Flt4-expressing cells with the secreted polypeptide with the molecular weight of about 23 kD, wherein the contacting of said Flt4-expressing cells with said polypeptide stimulates Flt4 activity in said Flt4-expressing cells.