RTN4 and hepatocellular carcinoma: Then, we used The Cancer Genome Atlas (TCGA) database to verify the expression levels of these three genes in HCC patients, and the results revealed that RTN4 was down-regulated in HCC patients (P < 0.001), whereas CSMD1 and Tob1 were up-regulated in HCC patients (P < 0.001) (Figure 4(b)).