Rapamycin, a small molecule inhibitor of the Akt/mTOR pathway used for the prophylaxis and treatment of GVHD, has been shown in vitro to selectively expand or preferentially preserve Treg over Tcon [80], thus attenuating GVHD also by shifting the balance of aggressive to protective type alloimmunity. This evidence concerns the gene AKT1 and graft versus host disease.