CTSF (cathepsin F) is a cysteine protease ubiquitously expressed in multiple tissues that functions as a thiol protease participating in intracellular protein degradation and turnover 1. The protein localizes to lysosomes and extracellular vesicles, where it exhibits cysteine-type endopeptidase activity 2. CTSF is involved in proteolysis and antigen processing via the MHC class II pathway. In cancer biology, CTSF demonstrates dual roles depending on context. A Mendelian randomization study identified CTSF as a potential therapeutic target for breast cancer, with elevated expression associated with increased disease risk (OR: 1.14, 95% CI 1.08-1.21) 3. Conversely, in non-small cell lung cancer, high CTSF expression correlates with favorable prognosis and anti-tumor immune effects through regulation of immune cell markers and immunomodulators 4. In gastric cancer, LINC00982-mediated upregulation of CTSF expression inhibits cancer progression via transcription factor HEY1 suppression 5. A familial papillary thyroid cancer pedigree identified CTSF mutations as the most promising candidate causative gene, with elevated expression in mutated tumors 6. Clinically, CTSF mutations have been associated with ceroid lipofuscinosis, neuronal, 13 (Kufs type), and identified as a genetic risk factor in amyotrophic lateral sclerosis and frontotemporal dementia 7. These findings suggest CTSF represents a pleiotropic gene with context-dependent roles in cancer progression and neurodegeneration.