FNBP1L (formin binding protein 1 like) is a membrane-associated protein essential for coordinating endocytosis with actin cytoskeleton reorganization. The protein contains FCH, FBH, HR1, and SH3 domains, with the FCH domain serving as a microtubule-binding domain and the SH3 domain interacting with formin and WASP family proteins 1. FNBP1L functions as a scaffold protein that promotes CDC42-induced actin polymerization by activating the WASL/N-WASP complex, facilitating membrane invagination and tubule formation during endocytosis 1. A critical function of FNBP1L is in antibacterial autophagy, where it interacts with ATG3 and is essential for autophagy of intracellular pathogens like Salmonella, serving to restrict bacterial growth 2. However, FNBP1L appears dispensable for other autophagy forms induced by starvation or rapamycin 2. The protein also contributes to cellular responses to mechanical stress, with its expression being regulated by cyclic stretch in periodontal ligament cells 3. In dendritic cells, FNBP1L functions as a restriction factor limiting HIV-1 entry, as its knockdown increases viral entry through enhanced endocytosis pathways 4. Recent studies have identified FNBP1L as a component of kidney podocyte foot processes, suggesting roles in maintaining glomerular filtration integrity 5.