A novel isoform of tropomyosin is disclosed. The isoform is closely related to epithelial human tropomyosin (hTM) and more particularly to hTM5 except the last coding exon. The novel isoform, is called TC22. Northern blot analysis with TC22-specific probe revealed that normal culture cell lines and normal epithelial tissues expressed very little, if at all, TC22 message, whereas their transformed counterparts and tumor tissues including dysfunction of the alimentary canal, significantly increased the expression of TC22. Assays directed at determining the level of TC22 are useful in diagnostics and therapeutics of dysfunction of the alimentary canal. Specific antibodies and mimics for TC22 are also disclosed for use in diagnostics and therapeutics of dysfunction of the alimentary canal.