AKT1 and Kaposi's sarcoma: In another study, human mesenchymal stem cells exerted anti-tumorigenic effects in a model of Kaposi’s sarcoma by inhibiting Akt activation in tumor cells, but had no effect when incubated with prostate tumor cell line PC-3 or breast cancer cell line MCF-7 suggesting cell specific inhibition of the Akt protein kinase [9].