Effect of normalization strategies on expression ratios. Normalized expression of ACT1, PDA1, IPP1, RDN18, GPH1, GSY2 and SGA1, in 5 characteristic samples during growth on glucose (i.e. set "B" in Figure 2): early exponential phase (respiro-fermentative), entry in (disappearance of glucose) and exit from the diauxic shift, mid of post-diauxic (respiratory) growth, and 3 days stationary phase. The exponential phase sample (S#1) was used as calibrator. Normalization was performed using the three most stable genes (NF(UBC 6, TAF 10, ALG 9), dashed bar), the following 3 best (NF(TFC 1, KRE 11, FRP 2), grey bar), ACT1 alone (NF(ACT 1), black diamond) or using ACT1, PDA1 and IPP1 (NF(ACT 1, PDA 1, IPP 1), empty diamond). Normalized expression data and error bars were calculated using the gene expression module of the BIORAD iQ5 software, which follows models and error propagation rules outlined in the geNorm manual. For the sake of clarity, we did not plot standard deviation of ratios obtained from NF(ACT 1, PDA 1, IPP 1).