The fragile histidine triad (FHIT) gene located in human chromosome 3p14.2 is a candidate tumor suppressor gene that has a diadenosine triphosphate (Ap3A) hydrolase activity, but its role in carcinogenesis remains uncertain. To investigate the role of FHIT in normal cells, specific polyclonal antibodies to recombinant rat FHIT protein were generated. Immunoblot analysis revealed the 17-kd FHIT protein was most abundantly expressed in kidney and liver, whereas heart, skeletal muscle, and adrenal gland expressed trace amounts. In kidney, immunohistochemical staining was strongly observed in distal convoluted tubule and collecting duct during postnatal growth period. By a nested reverse transcription-PCR analysis of FHIT from 2 human kidney cancer cell lines, four abnormal-sized FHIT transcripts, with deletion and/or insertion, were detected. These were derived from the results of exon skipping, and/or insertion of FHIT intron 5 sequence, or selection of cryptic splice site within the FHIT cDNA sequence 179-180. Taken together, our data indicate that FHIT expression is frequently altered in human kidney cancer cell lines by alternative splicing, and suggest that the FHIT protein may play a pivotal role in regulating intracellular metabolism of the distal convoluted tubule and collecting duct in maturity.