ApoA1 is a 29.0 kDa protein produced in the liver and intestine, and secreted as the predominant constituent of nascent high-density lipoprotein (HDL) particle. ApoA1 which is found exclusively in HDL has a unique ability to capture and solubilize free cholesterol. This ApoA-I ability enables HDL to remove excess peripheral cholesterol and return it to the liver for recycling and excretion. This process, called reverse cholesterol transport, is thoμght to inhibit atherogenesis. For this reason HDL is also known as the “good cholesterol.” The therapeutic potential of apoA-I has been recently assessed in patients with acute coronary syndromes, using a recombinant form of a naturally occurring variant of ApoA-I (called ApoA1 Milano). Rat ApoA1 s a 27.4 kDa protein of 235 amino acid residues.