MTOR and Kaposi's sarcoma: To further evaluate the contribution of the vGPCR-induced paracrine activation of mTOR to VEGF upregulation in vivo, we used an allograft model in which (SV-40) immortalized murine endothelial cells (SVECs) expressing vGPCR (EC-vGPCR) are mixed with SVECs co-expressing two non-tumorigenic KSHV latent genes, vCyclin and vFLIP (EC-vCYC/vFLIP), in a (1∶10) ratio that approximates the proportion of expressing cells in human KS (Fig. 1E) [15].