Composition comprises a substance which inhibits the expression or activity of a tumor-associated antigen, where the antigen has a sequence coded by a nucleic acid with specifically defined sequence. Composition comprises a substance (S1) which inhibits the expression or activity of a tumor-associated antigen (A1), where (A1) has a sequence coded by: a nucleic acid (I) with one of 29 specifically defined sequences given in the specification (SEQ ID 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 69, 71, 73, 75, 79, 80, 85, 87, 102, 104, 106, 108, 110 or 112); a nucleic acid (II) hybridizing to (I); a nucleic acid (III) degenerate with respect to (I) or (II); or a nucleic acid (IV) complementary to (I), (II) or (III). Independent claims are also included for the following: (1) composition comprising a substance (S2) with tumor-inhibiting activity selective for cells which exhibit an expression (optionally abmormal) of (A1); (2) composition containing a substance (S3) increasing the quantity of complexes between a human leukocyte antigen (HLA) and (A1) or its fragment; (3) diagnosis (M1) of diseases characterized by the expression or abnormal expression of tumor-associated antigens comprising the detection, in a biological sample isolated from a patient, of (I) or its fragment, (A1) or its fragment, (Ab) or its fragment, or cytotoxic or helper-T-lymphocytes specific for (A1) or its fragment; (4) treatment of diseases characterized by the expression or abnormal expression of tumor-associated antigens comprising removal of a patient sample with immunoreactive cells, contacting the sample with (C1) under conditions favoring the production of cytolytic or cytokine-releasing T-cells against (A1), and importing the cytolytic or cytokine-releasing T-cells into the patient in a quantity sufficient to promote lysis of cells expressing (A1); (5) treatment (M2) of diseases characterized by the expression or abnormal expression of tumor-associated antigens comprising ident