The transforming growth factor beta (TGF beta) binds the type II TGF beta growth factor receptor (TGF beta RII) to inhibit growth of most epithelial tissues. Most human colon cancers with microsatellite instability have frameshift mutations in two microsatellites within the TGF beta RII coding region; such mutations truncate the receptor to produce resistance to TGF beta. To investigate this pathway in other tissues, we surveyed sporadic human cancers of the pancreas, liver and breast to determine the frequency of microsatellite mutations in the TGF beta RII. We amplified genomic DNA segments containing two microsatellites plus 72% of domain XI of the serine-threonine kinase region. SSCP analysis showed no evidence of mutation in 32 sporadic cancers (12 pancreas, 10 liver, and 10 breast). We conclude that microsatellite mutations in TGF beta RII are uncommon in sporadic tumors of the pancreas, liver and breast.