Putative biological roles for SR-A. In vitro studies that have examined the breadth of SR-A activities, together with analyses of the SR-A–deficient mouse, have suggested a number of different biological roles for the receptor. These include the endocytosis of modified lipoproteins and its association with vascular disease; the adhesion of Mφ to the substratum and other populations of cells; the binding and ingestion of microbes; the detoxification of pathogen-specific components; and the phagocytosis of apoptotic or unwanted host cells.