A novel gene (designated 238P1B2) and its encoded protein, and variants thereof, are described wherein 238P1B2 exhibits tissue specific expression in normal adult tissue, and is aberrantly expressed in the cancers listed in Table I. Consequently, 238P1B2 provides a diagnostic, prognostic, prophylactic and/or therapeutic target for cancer. The 238P1B2 gene or fragment thereof, or its encoded protein, or variants thereof, or a fragment thereof, can be used to elicit a humoral or cellular immune response; antibodies or T cells reactive with 238P1B2 can be used in active or passive immunization.