A cancer vaccine containing a plasmid encoding the mammaglobin-A gene with potential immunostimulating and antineoplastic activities. Upon administration, mammaglobin-A DNA vaccine may induce both humoral and cytotoxic T lymphocyte (CTL) immune responses against tumor cells that express mammaglobin-A, which may result in decreased tumor growth. The 10 kiloDalton (kD) glycoprotein mammglobin-A is expressed in over 80% of human breast cancers.