A novel gene (designated 193P1E1B) and its encoded protein, and variants thereof, are described wherein 193P1E1B exhibits tissue specific expression in normal adult tissue, and is aberrantly expressed in the cancers listed in Table I. Consequently, 193P1E1B provides a diagnostic, prognostic, prophylactic and/or therapeutic target for cancer. The 193P1E1B 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 191P1E1B can be used in active or passive immunization.