Macrophage scavenger receptor 1 (MSR1), also known as CD204, is a homotrimeric transmembrane glycoprotein and class A scavenger receptor with roles in innate and adaptive immunity, and various pathophysiological processes, including non-alcoholic fatty liver disease (NAFLD).{65565,65566} It is primarily expressed on the surface of macrophages and dendritic cells but is also present on the surface of lymphocytes.{65566} MSR1 binds to a variety of ligands, including apolipoprotein E (ApoE), LDL, type III collagen, cholesterol, apoptotic cells, and pathogens, and induces intracellular signaling in a ligand-specific manner, to mediate phagocytosis, endocytosis, and lipid uptake. Levels of MSR1 are increased and associated with the incidence of hepatic steatosis, cirrhosis, and hepatocellular carcinoma in patients with NAFLD. An increased population of MSR1+ tumor-associated macrophages (TAMs) in tumor stroma compared with the primary tumor is correlated with poor prognosis and shorter survival time in patients with non-small cell lung cancer (NSCLC), uterine cervical adenocarcinoma, glioma, or muscle-invasive bladder cancer.{65565} Cayman’s MSR1/CD204 Rabbit Monoclonal Antibody (Clone 004) can be used for flow cytometry (FC), immunocytochemistry (ICC), immunofluorescence (IF), and immunohistochemistry paraffin (IHC-P) applications.