Real-time RT-PCR analysis of ART1, ART3 and ART5 mRNA expression in myogenic cell lines during skeletal muscle differentiation in vitro. The mRNA of C3H-10T 1/2 and C2C12 cells at different stages of differentiation (progenitors (Pg), MyoD-myoblasts (MoD-Mb), myoblasts (Mb), myotubes (Mt)) was isolated and mRNA levels of ART1, ART3 und ART5 were measured by semiquantitative real-time RT-PCR. Relative mRNA levels were standardized to the expression of beta-2 microglobulin housekeeping gene and mRNA concentrations from C3H-10T 1/2 cells (Mt) and C2C12 cells (Mt 6d, ART3 – Mt 3d) were set as the 100% reference. Asterisks indicate values less that 0.3%. Data are means ± S.D. of three independent experiments. n.d.: not detectable.