Thanks Gian for your response.
My next question is where I can find the column headers for the files that are in the GSE56227_RAW.tar package?
To me it looks these files contain ten columns but at least I cannot find any obvious explanation for their content.
I think most relevantly I would need to know which column contains to the RPKM values and which column(s) contain(s) gene identifiers.
Regarding the gene identifier, I would guess perhaps the fourth column (e.g. ENSMUSG00000042429, ENSMUSG00000025909) contains Ensembl Gene identifiers, right?
Are there possibly also some other gene identifiers (in other columns)?
Or is it perhaps so that this information is nowhere in GEO explicitly available?
If this is the case, perhaps then the only way to get explicit answers is to simply contact the corresponding author.
I am newbie to RNA-seq, so please forgive me if I am asking something trivial.