MSR1 (macrophage scavenger receptor 1) is a membrane glycoprotein that mediates endocytosis of modified lipoproteins, particularly acetylated and oxidized low-density lipoproteins, through receptor-mediated endocytosis 1. The receptor exhibits functional heterogeneity, with isoform III unable to internalize acetylated LDL 2. MSR1 plays a dichotomous role across multiple pathophysiologic processes, including atherosclerosis, innate immunity, and cancer 3. Mechanistically, MSR1 mediates lipid-induced inflammation via JNK signaling pathway activation, promoting foamy macrophage formation and pro-inflammatory cytokine release 4. In tumor microenvironments, MSR1 expression increases during monocyte-to-M2 macrophage differentiation, associated with transcriptional reprogramming and immunosuppressive phenotype acquisition 5. MSR1 also facilitates myelin debris clearance in microglia across dementia subtypes, with increased expression correlating with enhanced phagocytic activity 6. Clinically, MSR1 upregulation associates with hepatic steatosis and inflammation severity in non-alcoholic fatty liver disease, and MSR1 blockade prevents disease progression 4. Additionally, MSR1 repeats act as regulatory elements whose copy number variation influences breast and prostate cancer risk 7. MSR1 mutations were identified in hereditary diffuse gastric cancer families lacking CDH1 mutations 8.