SFI1 is a centrosomal protein that functions as a critical regulator of centriole architecture and duplication through its interaction with Centrin proteins. SFI1 contains approximately 20-23 binding sites for Centrin (CETN2), forming a conserved complex essential for centriole organization 1. In humans, the SFI1/Centrin complex localizes to the distal end of centrioles and is recruited early during procentriole assembly, where it controls centriolar architecture, CEP164 distribution, and CP110 removal during ciliogenesis 1. The mechanism involves SFI1 recruiting the deubiquitylase USP9X to the centrosome during S phase, which deubiquitylates and stabilizes STIL, a critical regulator of centriole duplication 2. Centrin binding to SFI1 is calcium-dependent and regulated by phosphorylation; CK2 phosphorylation of centrins reduces their binding affinity to SFI1 3. Clinically, mutations affecting SFI1 function and centriole duplication cause microcephaly in humans 2. Additionally, the long non-coding RNA SFI1-AS1 shows potential as a biomarker for coronary artery disease, exhibiting protective effects against CAD risk 4. This functional role in neurodevelopment through centriole regulation underscores SFI1's importance in maintaining proper brain development.