I want to analyse GE data at probe level. From the .CEL files I create with read.celfiles() a GeneFeatureSet object (oligoClasses). With exprs() I get the raw expression data. My question is: How I can get probeset_id (e.g 7896739) from this GeneFeatureSet, to map this to my annotation file?

The function featureNames() from Biobase creates a character vector starting with 1, which doesn't look like the 7-digit long probeset_id.

Thank you