, and oligomerizationdomains. It is postulated to bind to a p00-binding site and activate expression of downstreamgenes that inhibit growth and/or invasion, and thus function as a tumor suppressor. Mutants ofp00 that frequently occur in a number of different human cancers fail to bind the consensus DNAbinding site, and hence cause the loss of tumor suppressor activity. Alterations of this geneoccur not only as somatic mutations in human malignancies, 