Then we validated identified candidate reference genes by RT-qPCR on 39 fresh breast cancer biopsies and compared expression stability of these genes and commonly used control genes including ACTB, GAPDH, RPLP0, GUSB and TFRC that form a set of reference genes in a commercial Oncotype DX Breast Cancer diagnostic test [2]. The gene discussed is GAPDH; the disease is breast carcinoma.