TGFB1 and Autoimmunity: In addition, in vivo, mice with a TGFβ deficiency in FoxP3-expressing cells (including Tfr) (Foxp3cre.Tgfb1flox/flox) or with impaired TGFβ signaling in T cells (including Tfh) (Cd4cre.Tgfbr2flox/flox) develop fatal autoimmunity associated with increased frequency of Tfh and GC B cells (35, 38).