GC correction reduces, but does not diminish tissue-specificity in aCGH signal intensity. The red line depicts the GC content in percentage (secondary y-axis) across rat chromosome 16. The dashed black line shows the log2 aCGH signal intensity of brain versus testis (ACI rat strain). The black line shows the signal intensity after GC correction. Specific peaks at high GC regions are visibly removed (for example, at 18 Mb), while others are not (for example, at 28 Mb).