I have a large database of RNA-seqs of different cell lines. I'd like to get normalized gene expression levels for each of the cell lines. From what I've read so far it seems that normalizing gene expression is done compared to a reference or control (such as with DEseq). Since the cell lines are indepedent of each other I don't have one cell line that I would consider a control or a suitable refenrce point for gene expression levels.
Is there an accepted way for normlaizing gene expression levels for single samples without comparing to a control?