An elevated level of LDL cholesterol is associated with the development of atherosclerosis and is also associated with aging. Modification of LDL particle is one of the main contributors to the development of atherosclerosis and is elevated with increasing plasma LDL concentrations. Modified LDL is usually composed of LOOH/aldehydes, unfolded protein and some protein post-translational modifications. It has been debated whether the lipid peroxides or unfolded apoB-100 protein is important. An important pathway in atherosclerosis may be the phosphorylation of JNK-2 in ECs. OxLDL-R CD-36 knockout macrophages which have decreased foam cell formation and decreased JNK-2 phosphorylation as well as an ApoE and JNK-2 double knockout mouse has decreased lesion size and MFC formation. Foam cells have increased ROS production and mitochondria are the major source of ROS and this evidence may suggest that p-JNK-2 is involved in regulating mitochondrial function.