The observations that, NA (i) plays a role in atherosclerosis regression in humans and (ii) has the capacity to act directly on monocyte/macrophage function by up-regulating proteins that are involved in cellular cholesterol efflux, raise the important possibility that NA may exert effects, via its receptor GPR109A, in foam cells to induce cholesterol efflux, leading to plaque regression. The gene discussed is HCAR2; the disease is atherosclerosis.