As shown by immunohistochemical analysis in our study, 20.7% paraffin-embedded HCC cancer tissues showed strong membrane and cytoplasm staining of CTSL, 36.6% HCC tissues showed moderate CTSL staining and 42.7% showed negative staining in tumor cells, while the non-cancerous tissues presented mainly negative expression of CTSL, indicating that CTSL might play an important role in the development and progression of HCC. Here, CTSL is linked to hepatocellular carcinoma.