Normalisation of desmin mRNA expression to various combinations of the geometric average for two genes. Data shown are all calculated relative to day 2, so that day 2 values are equal to 1 arbitrary unit (A.U.). Six normalisation factors were derived by calculating the geometric averages of the following gene combinations: A: Hprt1, Ppia (closed circle); B: RNApolII, Hprt1 (open triangle); C: EF1α, Hprt1 (closed square); D: EF1α, Ppia (open diamond); E: RNApolII, EF1α(closed triangle); F: RNApolII, Ppia (open circle). Values shown are the mean normalised value ± S.E. (n = 6).