IBSP (integrin binding sialoprotein), also known as bone sialoprotein, is a highly glycosylated phosphoprotein that plays crucial roles in bone mineralization and cell-matrix interactions. The protein binds tightly to hydroxyapatite and appears to form an integral part of the mineralized matrix, functioning as a nucleator for hydroxyapatite crystal formation 1. IBSP promotes cell adhesion and migration through its RGD motif, which interacts with alpha-V/beta-3 integrin receptors 1. The gene is located on chromosome 4-q31 and contains six small exons plus one large exon, with expression induced in newly formed osteoblasts and regulated by hormones and cytokines that influence bone formation 21. IBSP expression is upregulated during osteoblast differentiation under Runx2 regulation 3. Clinically, IBSP has significant disease relevance, being highly expressed in bone metastatic lesions of lung adenocarcinoma where it promotes macrophage-to-osteoclast differentiation and osteolytic bone metastasis through RAC1-NFAT signaling 4. The protein also shows altered expression in periodontal disease, with decreased IBSP+ osteoblast fractions following periodontal therapy 5. IBSP represents a potential therapeutic target and diagnostic marker for bone-related pathologies.