I frequently hear (and read in papers) that there is a low correlation between gene expression and protein levels. But I don't get a good answer as to why we still do gene expression analysis.
Is this a valid reason: (Given that we know the limitation of the approach) we still have that the potential to get new biological insight/discovery.
Is it easier and cheaper to screen the genome-wide expression and then look for specific protein than to screen the entire proteome?
Or is there any other reason.