Antibodies and molecules derived therefrom that bind to 161P2F10B protein and variants thereof, are described wherein 161P2F10B exhibits tissue specific expression in normal adult tissue, and is aberrantly expressed in the cancers listed in Table I. Consequently, 161P2F10B provides a diagnostic, prognostic, prophylactic and/or therapeutic target for cancer. The 161P2F10B 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 161P2F10B can be used in active or passive immunization.