A detailed genetic map on human chromosome 11 was prepared. Then, a commonly deleted region on the chromosome in the tumor tissues of patients with multiple endocrine neoplasia type 1 was identified. Further, by linkage analysis on a family line with this disease, a gene causative of this disease was localized. A gene present in the region common to these observations was cloned and the structure of this gene was determined. Because a protein coded by this DNA is homologous with those of transcriptional factors, it is expected that the above-mentioned gene may be a novel tumor suppressor gene. Further, it is also expected that the above-mentioned gene and a protein coded for thereby may be useful in preparation of a remedy for cancer and a diagnostic drug for cancer.