Four examples of different correlation coefficients: 0.743, 0.498, 0.240 and 0.00 (from the top left to the bottom right) between expression levels of RNA and protein gene products with corresponding Ensembl IDs (ENSG00000106415, ENSG00000175305, ENSG00000130522 and ENSG00000072041, respectively). The two lines indicate RNA expression levels measured in oligo microarray (blue) and protein expression analyses (red), across 23 cell lines. The values shown have been adjusted to a comparable scale, by adding the absolute value of the lowest RNA oligo value (which is always negative) to all RNA oligo values. All values (RNA oligo and protein) have then been divided by the highest value for the RNA oligo data. This gives measurements on a comparable (0 – 1) scale and the correlation coefficient remains the same as before the adjustment.