Why is 18S ribosomal RNA (rRNA) used as a housekeeping gene to normalize sample-to-sample systematic variation in the qPCR assays?
Because of its invariant expression across tissues, cells and experimental treatments, 18S ribosomal RNA is a widely used control for most qRT-PCR analyses. However, due to its extremely high expression in most cell types, it can sometimes be challenging to use 18S rRNA as an endogenous normalizer for other gene expression assays in the same reaction.
