The lack of expression of the putative tumor suppressor gene DMBT1 has been described in gliomas, lung carcinomas, and other malignancies. To investigate the mechanisms regulating DMBT1 expression rye have screened a human genomic library with a 5' cDNA probe and identified a fragment of approximately 3 kb upstream of the proposed coding sequence of DMBT1. This fragment contains subregions that may up- or down-regulate the expression of a reporter gene. These findings may help to elucidate the mechanisms regulating the alternative splicing and the tissue specific expression of DMBTI.