A novel gene (designated 121P1F1) and its encoded protein, and variants
thereof, are described wherein 121P1F1 exhibits tissue specific
expression in normal adult tissue, and is aberrantly expressed in the
cancers listed in Table I. Consequently, 121P1F1 provides a diagnostic,
prognostic, prophylactic and/or therapeutic target for cancer. The
121P1F1 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 121P1F1 can
be used in active or passive immunization.