Presently, the technique of immunohistochemistry (IHC) has emerged as a promising tool for assessing the presence of HCC such as glutathione S-transferase pi (GSTP), proliferating cell nuclear antigen (PCNA), and tumor necrosis factor (TNF), indicating that integrating protein expression data with mRNA may offer a more effective means of predicting drug response (Márquez-Quiroga et al., 2022; Stärkel et al., 2015; Feng et al., 2022). The gene discussed is PCNA; the disease is hepatocellular carcinoma.