The present invention is directed to novel polynucleotides and the polypeptides encoded by them, each of which are specific to human prostate tumor cells. The present invention further provides chimeric polypeptide molecules comprising the polypeptides of the present invention fused to heterologous polypeptide sequences, and antibodies which bind to the polypeptides of the present invention. Also provided herein are methods for producing the polypeptides of the present invention, as are detection assays that detect the presence of tumor cells in tissue or bodily fluid samples and methods for identifying novel compositions which modulate the activity of prostate tumor antigens and the use of such compositions in diagnosis and treatment of disease.