In addition, metformin exerts in vitro chemo preventive effects through modulation of cytochrome P4501A1 (CYP1A1)/aryl hydrocarbon receptor (AhR) pathways.12 The anti-tumour effects of oral anti-diabetic therapy are not restricted to metformin, as thiazolidinediones (synthetic ligands of peroxisome proliferator-activated receptors γ – PPARγ) possess similar properties. The gene discussed is AHR; the disease is neoplasm.