A novel gene (designated 158P1D7) and its encoded protein are described. While 158P1D7 exhibits tissue specific expression in normal adult tissue, it is aberrantly expressed in multiple cancers including set forth in Table 1. Consequently, 158P1D7 provides a diagnostic and/or therapeutic target for cancers. The 158P1D7 gene or fragment thereof, or its encoded protein or a fragment thereof, can be used to elicit an immune response.