DLC1 contains 37 exons and spans approximately 59 kb. The predicted DLC1 protein contains 1,755 amino acids. Expression of DLC1 significantly suppressed the growth of 4 different cancer cell lines. Northern blot analysis revealed that DLC1 was expressed as 6- and 8-kb mRNAs in all tissues tested, most abundantly in prostate and testis. the 8-kb mRNA and several other alternatively spliced DLC1 transcripts contain disrupted coding regions and are likely to encode nonfunctional proteins. RT-PCR experiments indicated that 33% of primary lung, esophageal, and renal cancers and cancer cell lines tested either lacked DLC1 transcripts entirely or contained increased levels of nonfunctional DLC1 mRNA. The authors concluded that aberrant transcription of DLC1 may be involved in carcinogenesis of the lung, esophagus, and kidney.