"Oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV) K1 oncoprotein interacted with and activated PYCR enzyme increasing intracellular proline concentration. Consequently the K1-PYCR interaction promoted tumor cell growth in 3D spheroid culture and tumorigenesis in nude mice. This study demonstrates that an increase of proline biosynthesis induced by K1-PYCR interaction is critical for KSHV-mediated tumorigenesis."xsd:string