Macrophage scavenger receptor types I and II, also known as Macrophage acetylated LDL receptor I and II, Scavenger receptor class A member 1, CD24, MSR1, and SCARA1, is a single-pass type II membrane protein that contains one collagen-like domain and one SRCR domain. Macrophages are distributed in all peripheral tissues and play a critical role in the first line of the innate immune defenses against bacterial infection by phagocytosis of bacterial pathogens through the macrophage scavenger receptor 1 (MSR1). MSR1 / SCARA1 is one of the membrane glycoproteins implicated in the pathologic deposition of cholesterol in arterial walls during atherogenesis. Two types of receptor subunits exist. These receptors mediate the endocytosis of a diverse group of macromolecules, including modified low-density lipoproteins (LDL). MSR1 / SCARA1 is also involved in chronic inflammation which is a risk factor for prostate cancer. MSR1 1 gene was identified as a candidate susceptibility gene for hereditary prostate cancer and as a risk factor for sporadic prostate cancer.