Four commonly used "housekeeping" genes (GAPDH, ACTB, RPS20, TBP1) and the combined data of RPL41 and SFRS4 (see Figure 2C) were used for normalization to assess the effects their choice for normalization has on the fold changes of differentially expressed genes during the course of HCV-induced HCC. The gene discussed is RPS20; the disease is hepatocellular carcinoma.