COL4A1 and hepatocellular carcinoma: Gene expression analysis of paired tumor-non-tumor samples from TCGA-LIHC cohort (n = 438) also showed 1.13-(p < 0.001), 1.01-(p < 0.01), and 1.07-(p < 0.001) fold reduction in COL1A1, COL1A2 and COL4A1 mRNA expression in the HCC tumor compared to the non-tumor ‘normal’ liver samples (Figure 1D).