Described is a novel gene and its encoded basic Helix Loop Helix protein, termed PHELIX, and to diagnostic and therapeutic methods and compositions useful in the management of various cancers which express PHELIX, particularly including prostate cancer, bladder cancer, ovarian cancer and testicular cancer. In human normal tissues, PHELIX is only expressed in testis tissue. However, PHELIX is expressed at high levels in prostate cancer cells and in other cancer cells. The structure of PHELIX suggests that it may function as a transcription factor that normally exhibits a testis-specific expression pattern but is turned on in prostate cancer as well as in other cancers.