<prompt> Answer this question truthfullyWhat is the mechanism of action of Azathioprine6-MP and why are they useful in the treatment of graft rejection, SLE, autoimmune hemolytic anemia, etc.?  <response>: <reason> As per the information provided, Azathioprine6-MP have an immunosuppressive effect, which is why they are useful in the treatment of graft rejection, SLE, autoimmune hemolytic anemia, etc. 