Hi All, I am working on microarray GDS41 (pressure-overload induced cardiac hypertrophy) which is based on MGUAv1 chip. I used CEL files from GDS41 (version 1) and MGUAv2 CDF file (version 2). I get all the expression values whose total number of probesets is 12654 which corresponds to the one provided by version 1 chip. But I am wondering if the directions of probesets were fixed since I used the CDF version 2. Would it be ok to combine different vergions of CEL files and CDF file? Any suggestions would be appreciated. Regards, Ryosuke Kadoi