Each GeneChip® expression array listed below features approximately 100 maintenance genes which serve as a tool to normalize and scale your data prior to performing data comparisons.

To facilitate the use of these genes in scaling or normalization, the mask files that identify these maintenance probe sets on each array are available below.

Please see Appendix G of the GeneChip Operating Software Manual for a complete description on how to use mask files in scaling or normalization to selected probe sets.

Note: During the installation procedure, please ensure that the mask files are installed into the Library folder of Affymetrix Microarray Suite (GeneChip\Library) or GeneChip Operating Software (GeneChip\Affy_Data\Library). If you have inadvertently installed the mask files into a different folder, simply copy the files into the Library folder using Windows Explorer.

GCOS Note: GCOS v1.2 systems (Client and Server) require the 1.2.1 udpate to process mask files for Comparison Analysis. Download the update.