Figure 3.

AR protein expression during sASC chondrogenesis and norepinephrine (NE)-mediated activation of intracellular signaling. (A) Immunohistochemical analysis of β2-AR and α2a-AR during sASC chondrogenesis on days 1, 7, 14, and 21 of differentiation (bars, 500 μm in upper panels and 50 μm in lower panels). (B) Western blot analysis of total ERK1/2 as well as ERK1/2 phosphorylation in chondrogenic sASC culture in the absence or presence of NE (10⁻⁸ M and 10⁻⁶ M, representative blot of one OA patient).