Transforming growth factor-β receptors type I, II and III in phenobarbital-promoted rat liver tumors

Rat liver tumors initiated with N-nitrosodiethylamine (DEN) followed by promotion with phenobarbital (PB) were examined for expression of transforming growth factor-β (TGFβ) type I, II and III receptors. RNase protection and TGFβ 1 affinity labeling asays were used to determine TGFβ receptor steady-state mRNA and protein levels, respectively. We have demonstrated that all three TGFβ receptors are expressed in both normal and malignant hepatic tissues. Long-term PB administration did not alter TGFβ receptor mRNA or protein levels in normal liver