The candidate tumor suppressor gene,FHIT(Fragile histidine triad protein),encompasses the common human chromosomal fragile site at 3p14.2,the hereditary renal cancer translocation breakpoint,and cancer cell homozygous deletions. Fhit hydrolyzes dinucleotide 5',5'''-P1,P3-triphosphate in vitro and mutation of a central histidine abolishes hydrolase activity. FHIT has a major role in regulating beta-catenin-mediated gene transcription.