POSTN (periostin) is an extracellular matrix protein that plays crucial roles in cell adhesion, tissue remodeling, and disease pathogenesis. The protein induces cell attachment and spreading, functioning as a cell adhesion molecule 1. In pathological contexts, POSTN is prominently expressed by cancer-associated fibroblasts (CAFs) and activated fibroblasts across multiple diseases. POSTN+ CAFs create immunosuppressive microenvironments in hepatocellular carcinoma and non-small cell lung cancer by hindering T-cell infiltration and promoting immune evasion 23. The protein mediates tumor progression through integrin-FAK-STAT3 signaling pathways, promoting cell proliferation and epithelial-mesenchymal transition 45. In cardiac disease, POSTN+ fibroblasts emerge following injury and contribute to tissue fibrosis through IL-1β-mediated immune-fibroblast communication 6. POSTN expression is associated with poor prognosis in multiple cancers and represents a potential therapeutic target 35. Additionally, POSTN is upregulated in pulmonary fibrosis, where it contributes to excessive collagen production and tissue scarring 7. The protein's role in extracellular matrix remodeling and its association with disease progression makes it a promising biomarker and therapeutic target across multiple pathological conditions.