TSPO1, or Translocator Protein 18 kDa, is primarily involved in the regulation of mitochondrial function and cellular stress responses. It plays a key role in the transport of cholesterol across the mitochondrial membrane, which is a critical step in the synthesis of steroid hormones in endocrine tissues such as the adrenal glands and gonads. Due to its upregulation in activated microglia during neuroinflammation, TSPO1 is widely used as a biomarker in neuroimaging studies, particularly in positron emission tomography (PET), to monitor neurological conditions like Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Ligands targeting TSPO1 are also being investigated for their potential anxiolytic, anti-inflammatory, and neuroprotective effects, making it a significant target in drug development for psychiatric and neurodegenerative disorders. Additionally, its expression in various cancers has led to research into its use for tumor imaging and oncology therapeutics.