LIG4 and atherosclerosis: Plaque VSMCs also show differences in expression of multiple DNA damage repair proteins, indicative of activation of a DNA damage repair response.11 Some human DNA damage syndromes are associated with premature atherosclerosis, and previous studies in mice have shown that knockout of some DNA repair enzymes can promote atherosclerosis or vascular dysfunction,8,38 suggesting that DNA damage may promote atherosclerosis.