Everolimus is a proliferation signal inhibitor that prevents allograft rejection. It exerts its immunosuppressive effect by inhibiting the proliferation, and thus clonal expansion, of antigen-activated T-cells, which is driven by T-cell-specific interleukins. Everolimus inhibits an intracellular signaling pathway that is triggered up binding of these T-cell growth factors to their respective receptors, and which normally leads to cell proliferation. The blockage of this signal by everolimus leads to an arrest of the cells at the G1 stage of cell cycle.