I wanted some help in my real time pcr data analysis. I want to study expression levels of a gene, say gene X on a 24 hour scale. i.e. I want to study how expression levels on gene x varies across a day. I use a ribosomal protein gene ( house keeping gene) as my control. So if i have to calculate the fold increase in my gene X using comparative Ct method , given that i have Ct values for gene X and endogenous control can i use equation fold increase = 2^ (Ct control-Ct gene X)? Because technically comparative Ct methods uses 2^( (Ct control-test gene)in test/treated sample- (Ct control-test) in control/untreated sample). This applies for studies where you have a treated and untreated sample which is not the same in my case. All i have is a single tissue sample and i want to know the expression level of gene x relative to endogenous control.