The expression levels of netrins were upregulated in satellite cells during myogenic differentiation. Satellite cell primary cultures, prepared as shown in Figure 1, were maintained in differentiation medium (DM) after the induction of proliferation. (panel A) The mRNA expression of netrin-1, -3, and -4 and Sema3A was evaluated by real-time RT-qPCR normalized to the level of HPRT at all time points indicated. The bars depict the mean ± SEM of three independent cultures by relative units, as compared to differentiation at 0 h. As netrin-3 expression could not be detected at 0 h, relative units were compared to the 24 h time point. Significant differences from the mean of 0 h (the left-most open bar) at p < 0.05 and p < 0.01 are indicated by single and double asterisks, respectively. (panel B) The protein expression of netrin-1 was detected with ECL-Western Blotting standardized to β-actin expression level.