Characterization of differentiation of control and SMN-deficient ES cells. Control (C) and SMA (S) ES cells as described in 3A were processed for western blotting using antibodies against neurofilament (NF), Hb9, and ChAT respectively. The same blot was stripped and re-probed with anti-ERK antibody for protein loading control (A). Signals of three independent experiments were quantified, normalized to ERK, and plotted as for 3B. Differentiated control and SMA ES cells show similar levels of expression for neuronal and motor neuron marker proteins (B). Undiff. = undifferentiated cells and Diff. = differentiated cells.