Figure 4

MA plot (log-ratio of the expression intensities versus the mean log-expression of the intensities) for a typical ToxArray™ hybridization containing a mouse liver experimental RNA sample (Cy5-labeled) and Stratagene Universal Reference RNA (Cy3-labeled), each with A. thaliana spike-in control RNA added prior to labelling. The green circles indicate the mouse genes and red circles are the Rpl5 gene which reached scanner saturation in the Cy3 channel at many spots. The EC series covers the full range of signal intensities with no signal gaps. The LOWESS fit shown is through the external controls only, with a span of 0.3.