PLK1 and urinary bladder carcinoma: Recently, a group of researchers found that MSCs-released exosomes carrying polo-like kinase 1 (PLK-1) siRNA leading to apoptosis and necrosis in bladder cancer cells.146 Pascucci et al were the first to investigate the ability of MSCs-derived exosomes to encapsulate and deliver PTX as a chemotherapeutic agent.