You can find alternative CDF related to the paper of Dai et al. NAR 2005 at: http://brainarray.mbni.med.umich.edu/Brainarray/Database/CustomCDF/gen omic_curated_CDF.asp I have used them and in my personal experience the RefSeq remapping works better than Entrez Genes remapping. In our hands some qPCR validated probe sets based on Affy probesets are lost using the Entrez Genes (EG) based custom CDFs. Furhtermore, comparing fold changes between the same subset of genes identified using Affy probesets or EG based probesets a generalized reduction of fold change range was observed. Best Raffaele -- ---------------------------------------- Prof. Raffaele A. Calogero Bioinformatics and Genomics Unit Dipartimento di Scienze Cliniche e Biologiche c/o Az. Ospedaliera S. Luigi Regione Gonzole 10, Orbassano 10043 Torino tel. ++39 0116705420 Lab. ++39 0116705408 Fax ++39 0119038639 Mobile ++39 3333827080 email: raffaele.calogero at unito.it www: www.bioinformatica.unito.it