The basic immunosuppressive protocol involves the use of multiple drugs, each directed at a discrete site in the T-cell activation cascade. The prevailing paradigm regarding the mechanisms of action of immunosuppressants is that they function to prevent allograft rejection by preventing cell activation, proliferation and/or cytokine production. A new hypothesis is that some of the immunosuppressants might function by stimulating the expression of immunosuppressive molecules and/or cells.