PROCR (protein C receptor) is a cell surface receptor that binds activated protein C and enhances its activation by the thrombin-thrombomodulin complex, playing a central role in anticoagulant signaling 1. Beyond its canonical coagulation function, PROCR marks functionally distinct cell populations across tissues with diverse roles. In articular cartilage, PROCR+ cells represent mechanosensitive chondroprogenitors essential for cartilage maintenance and regeneration, responding to mechanical stimuli via Piezo1 signaling; genetic ablation of these cells accelerates osteoarthritis progression 2. PROCR+ fibroblasts secrete calcified apoptotic vesicles that initiate heterotopic ossification through calcium enrichment and extracellular matrix stiffening 3. In hematopoiesis, PROCR serves as a reliable surface marker for identifying functional hematopoietic stem cells in expansion cultures 4. Pathologically, tumor-expressed PROCR suppresses anti-tumor immunity by promoting IL-6 production, inhibiting Th1 differentiation and impairing CD8+ T cell function; radiation upregulates PROCR expression, contributing to radiotherapy resistance 5. PROCR+ endothelial progenitor cells can be depleted by reprogrammed tumor-associated macrophages to suppress angiogenesis 6. In retinal neovascularization, EPCR promotes pathological angiogenesis through heme catabolism and carbon monoxide release 7. Additionally, PROCR is exploited by malaria parasites as a binding target for severe disease pathogenesis 8.