CD4 and autoimmune disease: To investigate the molecular mechanisms by which Lkb1 controls Treg cell function, we compared the transcriptional profiling of CD4+YFP+ Treg cells sorted from Foxp3Cre/+ mice with that from Foxp3Cre/+Lkb1f/f mice lacking autoimmune diseases, thus avoiding the secondary impact of the inflammatory environment on Treg cell gene expression (Supplementary Data 3).