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Fig. 1. Effects of BMP4 and Notch signaling on C2C12 differentiation. (A) C2C12
cells were analyzed 6 days post-addition of differentiation medium, and after
BMP4 (50 ng/ml) and/or
-secretase inhibitor (L-685,458; 1 µM)
treatment. Myocyte differentiation was visualized by immunostaining for MHC
(red; left panel) and DAPI staining (blue; right panel) was used to identify
cell nuclei. Note that a considerable proportion of the cells were
MHC-positive under normal differentiation conditions (no addition), and that
the addition of BMP4 strongly reduced differentiation (BMP4). Treatment with
L-685,458 (L-685,458) led to an increase in the number of differentiated cells
compared with treatment with differentiation medium alone, and the combined
treatment with BMP4 and L-685,458 (L-685,458 + BMP4) resulted in an increase
in the number of MHC-positive cells, as compared with treatment with BMP4
alone. (B) C2C12 cells were analyzed for MHC expression 2 days post-addition
of differentiation medium in the presence of BMP4 (50 ng/ml), and after
transfection of CSL R218H (upper panel) or ß-gal (lower panel).