Isoform 1 is specifically expressed in leukemias and a variety of solid tumor cell lines and is also detected in testis and heart. Isoform 2 is predominantly expressed in testis and weakly expressed in tumor cells. Isoform 1 is the dominant immunogenic isoform and is capable of eliciting a humoral response in individuals with a variety of solid tumors. Expression of isoform 1 in a wide variety of malignancies as well as the presence of an immunogenic epitope suggest that it may be a suitable target for antigen-specific immunotherapy. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay.