TRERF1 and type 1 diabetes mellitus: As mentioned above, RAPA is an inhibitor of cell cycle progression and cytokine signal transduction preferentially in Teff cells, mainly Th1 and Th17, with a very weak or no impact on Tregs [45,46,47]; an exception was one very small study showing the beneficial impact of low doses of RAPA in monotherapy on refitting Treg suppressive function in long-term T1D subjects [76].