CTSO and glioblastoma: We analyzed the relationship between cathepsins and GBM based on the GEPIA database and found that CTSS, cathepsin C (CTSC), cathepsin K (CTSK), cathepsin O (CTSO), CTSB, CTSL, CTSZ/X, and CTSD were highly expressed in GBM (Figure 1), while only CTSB, CTSD, CTSL, and CTSZ/X (p < 0.05) were associated with overall survival (OS) (Figure 2).