SBF1 (SET binding factor 1), also known as MTMR5, is a multifunctional protein that primarily acts as an adapter and regulator of cellular trafficking and autophagy processes. SBF1 functions as an adapter for the phosphatase MTMR2, regulating its catalytic activity and subcellular localization, and may act as a guanine nucleotide exchange factor (GEF) for RAB28 12. The protein plays a critical role in autophagy regulation, particularly acting as a suppressor of autophagy in neurons by controlling phosphoinositide dephosphorylation essential for autophagy initiation and autophagosome maturation 3. Disease-wise, SBF1 mutations cause Charcot-Marie-Tooth disease type 4B3 (CMT4B3), a rare autosomal recessive peripheral neuropathy with early onset and severe presentation 45. In CMT4B3 patient fibroblasts, SBF1 dysfunction leads to selective mitophagy activation while impairing normal macroautophagy responses, revealing an uncoupling between these processes 6. Additionally, SBF1 expression levels correlate with gemcitabine sensitivity in head and neck squamous cell carcinoma, suggesting potential biomarker applications in cancer treatment 7. A GCC repeat polymorphism in the SBF1 gene has been associated with late-onset neurocognitive disorders, including Alzheimer's disease 8.