A method of suppressing angiogenesis in a mammal (e.g., for treating tumors, tumor metastasis or a condition that would benefit from decreased angiogenesis) comprises the step of administering to the mammal an angiostatically effective amount of a pharmaceutical composition comprising an isolated antiangiogenic truncated tryptophanyl-tRNA synthetase (TrpRS) polypeptide or an isolated nucleic acid that comprises a polynucleotide sequence that encodes the truncated TrpRS polypeptide. The truncated TrpRS polypeptide comprises residues 71-471 of SEQ ID NO: 10, residues 48-471 of SEQ ID NO: 10, or a polypeptide of approximately 47 kD molecular weight produced by cleavage of the polypeptide of SEQ ID NO: 10 with polymorphonuclear leucocyte elastase.
