Expression of α1- and β1-ARs. (a) Positive staining for β1-ARs in undifferentiated cells, cells pre-induced for 24 hrs with bFGF, EGF and PDGF-AA, and cells at 30 days of differentiation. Scale bar, 100 μm. (b) Nuclear expression of α1-ARs in undifferentiated cells, intensive nuclear staining in cells pre-induced for 24 hrs with bFGF, EGF and PDGF-AA, and surface expression at 30 days of differentiation. (c) Nuclear expression of α1-ARs in undifferentiated cells and evidence of a significant increase in staining intensity after 24 hrs treatment with bFGF alone. Scale bars, 100 μm, (40x magnification)