PPIB and Kaposi's sarcoma: Interestingly, rapamycin has been shown to induce the regression of KS tumours that had developed in transplant recipients on an immunosuppressive regimen containing the cyclophilin inhibitor cyclosporin [239], suggesting that the PI3 K/Akt/mTOR pathway might represent a promising target to interfere with the proliferation of KSHV-infected endothelial cells and to inhibit the development of KS.