BIRC5 and cancer: To restore drug sensitivity and further enhance antitumor effects, the hybrid siRNA anti-Survivin and anti-MDR1 (siSM) were treated as a model therapeutics via a PGS delivery system, resulting in a knockdown of Survivin and MDR1 and further sensitizing cancer cells to the drug cisplatin (DDP), PGS complexes were injected intravenously into a lung in situ tumor model, and it was found that PGS/siSM relatively reduced the growth rate of tumors, while simultaneous administration of PGS/siSM and DDP enhanced this effect (35).