DNA methylation is an active mechanism in the regulation of ABCB1 expression.30 Epigenetic mechanisms such as DNA methylation could also constitute a possible mechanism by which obesity—as assessed by BMI—could affect P-gp expression.30 It is well-known that obesity per se is often related to a variety of potentially stressful responses such as insulin resistance, altered nutritional status and chronic low-grade inflammation.31, 32 Moreover, obesity is known to be associated with an increased cancer risk,32, 33 which might also reflect deleterious epigenetic alterations. This evidence concerns the gene PGP and Insulin resistance.