The increased expression level of this gene is associated with HER-2/neu proto-oncogene overexpression. Amplification and resulting overexpression of this proto-oncogene are found in approximately 30 % of human breast and 20 % of human ovarian cancers. Further characterization of the product of this gene may yield insight into the fundamental biology and pathogenetic effects of HER-2/neu overexpression in human breast and ovarian cancer cells. Alternatively spliced variants encoding different isoforms have been identified for this gene.Synonyms: Cancer susceptibility candidate gene 4 protein