For the expression profiles generated, we regressed out technical variables including mRNA concentration, age of the block, batch (96-well plate), percent of the probes on the array detectable above the background, log transformed average background signal, and the median of the perfect match probes for each probe intensity of the raw data. The residuals were then shifted to have the original mean expression values and normalized using the RMA method. We mapped gene names to Affymetrix transcript cluster IDs using the NetAffx annotations as implemented in Bioconductor annotation package pd.hugene.1.0.st.v1; this resulted in 20,254 unique named genes. As gene names were used in the final analysis, this is what we have included in the sample tables.
