This August 2005 data freeze provides estimate of mRNA expression in adult brains of F2 intercross mice (C57BL/6J x DBA/2J F2) measured using Affymetrix M430A and M430B microarray pairs. Data were generated at The Oregon Health Sciences University (OHSU) in Portland, Oregon, by John Belknap and Robert Hitzemann. Data were processed using the Microarray Suite 5 (MAS 5) protocol of Affymetrix. To simplify comparison between transforms, MAS 5 values of each array were log2 transformed and adjusted to an average of 8 units. In general, MAS 5 data do not perform as well as RMA or PDNN transforms.