CTSL and hepatocellular carcinoma: To further investigate whether CTSL could enhance the proliferation and tumor progression ability of HCC cells (MHCC-97H) and colorectal cancer cell lines (CaCO2), we established stable MHCC-97H cell line and CaCO2 cell line that expressed CTSL (MHCC-97H-CTSL or CaCO2-CTSL) or empty vector (MHCC-97H-Con or CaCO2-Con).