SRSF4 and hepatocellular carcinoma: In our ARPP-19 qPCR assay, the housekeeping genes, TATA-binding protein (TBP) and arginine/serine-rich splicing factor 4 (SFRS4 or SRSF4), were used as internal control genes, because TBP and SRSF4 were considered as the most reliable reference genes for q-PCR normalization in HBV- or HCV-related HCC specimens, respectively [18,19].