I was trying to analyse expression levels of certain genes after treatment of monocytic THP1 cell line with antigenic proteins through qPCR and i tried using the reference genes beta actin and GAPDH but for both of them Cq values are not same for treated and untreated cells. Is there any way that i know the reference genes that are stable under the treatment? or should it depend on the cell line also? that case what about using macrophage cell lines?