Differentiation and myogenin expression. (A) Differentiation ability in the C2C12 and C2T18 is shown as CK activity, relative to nuclei numbers in GM at day 4 after plating and in DM at day 7 after serum lowering; for C2C12, differentiation was also evaluated after addition of hypomethylating drugs (DM+DH). Standard deviations (sd) are reported. The overall significant difference between conditions was evaluated by ANOVA (p < 0.0001); the significance of differences between each experimental condition pair was evaluated by Bonferroni's post test (see Sup. Table 3A); the only non-significant differences are those between C2T18 GM and both C2C12 DM and C2C12 DM+DH. (B) Northern blot shows myogenin expression, at indicated time after plating in GM or after serum lowering in DM, in C2C12 (even with addition of hypomethylating drugs (DM+DH)) and C2T18, as well as in embryonic tissues. Ribosomal 18S RNA is also shown for normalization. Columns indicate the mean of densitometric O.D. ratio (and corresponding sd) between myogenin and 18S signals of three independent northern blots. The overall significant difference between conditions was evaluated by ANOVA (p < 0.0001); the significance of differences between each experimental condition pair was evaluated by Bonferroni's post test (see Sup. Table 3B); the only non-significant differences are those between the following pairs: embryonic muscle (EmM) and C2T18 DM, embryonic brain (EmB) and C2C12 GM 48 h, C2C12 DM and C2T18 GM 96 h.