Any idea of which housekeeping gene has more stable expression in A431 and SCC-13 cell lines (squamous cell carcinoma), in order to use it as reference gene in my qPCR? Didn't have any lack with 18S so far!
Have you conducted a reference gene study? You can include a panel of genes such as GAPDH, Beta-Actin, PPIA, HPRT (and others) to assess the stability of one or more reference gene for the purposes of normalization. Popular methods include RefFinder, geNorm and BestKeeper. Some real time analysis software even offer these methods as a built-in functionality.
My lab team had been using 18s for these cells so I haven't, but I am getting different results while my gene of interest values seem more ok! These are very good suggestions actually, thank you!