KLKB1 and hepatocellular carcinoma: In addition, IHC analysis was performed to assess the MMP9, ESR1, CAT, FOS, and KLKB1 expression in HCC patients and the expression level of characteristic IRGs (MMP9, ESR1, CAT, FOS, and KLKB1) of IHC were scored blindly and compare to each other using a semi-quantitative analysis method (Figure 3).