Abstract: The present invention relates to polynucleotides associated with apoptosis-related disorders. The present invention also relates to canine and feline TRAIL genes, novel genes associated with apoptosis-related disorders, such as cancer. The invention encompasses TRAIL nucleic acids, recombinant DNA molecules, cloned genes or degenerate variants thereof, TRAIL gene products and antibodies directed against such gene products, cloning vectors containing mammalian TRAIL gene molecules, and hosts that have been genetically engineered to express such molecules. The invention further relates to methods for the identification of compounds that modulate the expression of TRAIL genes and gene products and to the use of such compounds as therapeutic agents in the treatment of apoptosis-related disorders, e.g., cancer. The invention also relates to methods for the diagnostic evaluation, genetic testing and prognosis of apoptosis-related disorders, e.g.