HPRT1 and prostate carcinoma: Souza et al. (2013) proposed GAPDH and SDHA genes as an optimal combination for RT qPCR data normalization in primary culture of prostate cells, Mori et al. (2008) suggested GAPDH and ACTB as suitable controls for FFPE-embedded prostate tissue, while HPRT1 and TBP were the most appropriate genes for prostate cancer metastases into the lymph nodes (Tsaur et al., 2013), thus confirming a prerequisite analysis of external reference control prior to evaluation of target gene in prostate cancer cells.