A novel gene 282P1G3 and its encoded protein, and variants thereof, are described wherein 282P1G3 exhibits tissue specific expression in normal adult tissue, and is aberrantly expressed in the cancers listed in Table I. Consequently, 282P1G3 provides a diagnostic, prognostic, prophylactic and/or therapeutic target for cancer. The 282P1G3 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 282P1G3 can be used in active or passive immunization.