sentence: Despite this finding , Tregs generated in the presence of RA are capable of suppressing skin graft rejection [ 49 ] , collagen induced arthritis [ 59 ] and allow the generation of mixed chimerism in transplant tolerance [ 63 ] suggesting that RA may also participate in the induction of other homing receptors.In agreement with a role for RA in Treg induction , the administration of the pan-RAR antagonist LE540 in mice challenged with Listeria monocytogenes significantly reduces the number of mucosal Foxp3 Tregs [ 64 ] .