ARG1 and atherosclerosis: Consistently, deficiency in myeloid cells of either the enzyme arginase 1 (Arg1), which converts arginine to ornithine, or the enzyme ornithine decarboxylase (ODC), which mediates the decarboxylation of ornithine to putrescine (Figure 2), is associated with efferocytic dysfunction and defective atherosclerosis resolution (105).