MFN1 (mitofusin 1) is a mitochondrial outer membrane GTPase that plays a crucial role in mitochondrial fusion and dynamics 1. The protein mediates mitochondrial fusion by forming homotypic and heterotypic complexes with MFN2, with both proteins being essential for maintaining mitochondrial network integrity 1. MFN1 functions through GTPase activity to promote outer mitochondrial membrane fusion, and embryonic fibroblasts lacking MFN1 display severely fragmented mitochondria due to reduced fusion capacity 1. The protein is critical for embryonic development, as MFN1-deficient mice die in midgestation 1. Beyond its fusion role, MFN1 participates in the senescence-associated secretory phenotype (SASP) by facilitating mitochondrial dsRNA release into the cytosol, which drives inflammatory responses in senescent cells 2. Dysregulation of MFN1 and mitochondrial dynamics has been implicated in various diseases including heart disease, type 2 diabetes, and cancer 34. Additionally, MFN1 can be inhibited by proteins like FUNDC2 in cancer cells, leading to mitochondrial fragmentation that promotes tumorigenesis 5. The protein's function is essential for maintaining mitochondrial membrane potential and overall cellular health 1.