Our measure of expression for each probe set was the median log2 signal intensity of perfect-match probes without SFPs. We used negative control probes to estimate the background intensity, and removed probes below this threshold.

Data may have been normalized prior to entry into GeneNetwork using 2z + 8 transform. This method simply stabilizes the variance of all array data sets, and resets the z score to 8 (rather than 0).