In the same population, Lovinsky-Desir et al. 2017 examined the association between physical activity, BC and buccal cell DNA methylation of the forkhead box p3 (FOXP3) gene promoter, a proposed biomarker of Treg activity, which increases with exercise and suppresses airway inflammation, but decreases in association with exposure to air pollution. This evidence concerns the gene FOXP3 and breast cancer.