Specially, COL4A1/COL4A2 were highly correlated with PXDN (r = 0.8937 / 0.8904) and SPARC (r = 0.8882 / 0.9124), reflecting significant changes in the extracellular matrix of HCC (Figure 6D). The gene discussed is COL4A2; the disease is hepatocellular carcinoma.