The invention concerns compositions and methods for the diagnosis and treatment of neoplastic cell growth and proliferation in mammals, including humans. The invention is based upon the identification of genes that are amplified in the genome of tumor cells, such as renal cell carcinoma. Such gene amplification is expected to be associated with the overexpression of the gene product as compared to normal cells of the same tissue type and contribute to tumorigenesis. Accordingly, the proteins encoded by the amplified genes are believed to be useful targets for the diagnosis and/or treatment (including prevention) of certain cancers, such as renal cell carcinoma, and may act as predictors of the prognosis of tumor treatment. The present invention is directed to novel methods of diagnosing and treating tumor, such as renal cell carcinoma or Wilms tumor.