This invention provides an isolated polynucleotide encoding an ECA1 polypeptide. Also provided is the isolated ECA1 polypeptide Further provided is an antibody that specifically recognizes and binds the ECA1 polypeptide or an epitope thereof. The polynucleotides, antibodies and/or polypeptides of this invention may be components of compositions, host cells and/or gene delivery vehicles, where appropriate. In one aspect, the host cell will produce recombinant ECA1, which is further defined herein. In another aspect, the host cell is an antigen presenting cell such as a dendritic cell, and it will display an antigenic portion of the ECA1 polypeptide on its surface. The polypeptides, proteins and compositions of this invention are useful to aid in the diagnosis of a neoplastic condition of a cell of endometrioid origin. In one aspect, the method comprises detecting the presence of an overexpressed ECA1 proto-oncogene in a sample suspected of containing said cell, wherein said overexpression is indicative of the neoplastic condition of said cell. These neoplastic cells include, but are not limited to ovarian and colon carcinoma cells.