The initial analysis of generated affymetrix data was performed with their MAS 5.0 software.The chip data were scaled to 500,then exported as text files to be loaded into the Genespring 6.0 program (Silicon Genetics,Redwood City,CA).The prescaled data were normalized by using the normalization steps”per chip to 50th percentile” and “per gene to median” as recommended by the manufacturer.