Transforming growth factor-beta (TGF-beta) is a growth regulator which affects multiple cellular functions through the TGF-beta type I and type II receptor (TGF-beta RI and TGF-beta RII) serine/threonine kinases. In this study, the expression of TGF-beta RI and RII was investigated by northern blot, reverse transcription-polymerase chain reaction (RT-PCR) and western blot analyses in human breast (MCF-7 and T-47D), ovary (CP70 and OVT2) and prostate (LNCaP, DU145 and PC3) cancer cell lines. Northern blot analysis showed expression of TGF-beta RI and TGF-beta RII mRNAs in all cell lines examined except for MCF-7 and LNCaP, respectively. In contrast, RT-PCR showed that all of the cell lines examined express TGF-beta RI and RII transcripts using specific primer oligonucleotides. Western blot analysis demonstrated that all of the cancer cell lines examined express TGF-beta RI and RII proteins. Southern blot analysis showed there were differences in the restriction enzyme digestion patterns for TGF-beta RI and RII of T47D compared to MCF-7, PC3 and LNCaP. Also, the addition of TGF-beta 1 to the breast and prostate cancer cells inhibited colony formation in soft agarose. Our studies show that in cancer cells, relatively low levels of TGF-beta receptor transcripts may result in protein production and inhibition of cell proliferation by TGF-beta.