Expression of activin receptor mRNA and protein in adult rat DRG neurons. A, Reverse transcriptase-PCR revealed strong expression of mRNAs for ActRI, ActRIB, and ActRII and weak expression of ActRIIB mRNA in the rat DRG neurons. B, ActRIB, ActRII, and ActRIIB immunoreactivity were detected by Western blotting of proteins from cultured rat DRG neurons. Western blotting revealed an ∼52 kDa ActRIB immunoreactive band, an ∼70 kDa immunoreactive band for unglycosylated ActRII, and 2 85–90 kDa bands for glycosylated ActRII as well as an ∼70 kDa immunoreactive band for ActRIIB.