As well, since atherosclerosis is promoted by M1 macrophages [46] and asthma and allergies are worsened by M2 skewed macrophages, reducing ATRA, PGE2 and/or TGFβ may prove efficacious in reducing the symptoms of allergies, asthma and the incidence and progression of cancer while increasing these factors might reduce certain forms of heart disease. This evidence concerns the gene TGFB1 and atherosclerosis.