sentences:  Survivin is known to be highly expressed in most tumour cell types and absent in normal cells, making it a good target for cancer therapy.The exploitation of survivin's over-active promoter in most cancer cell types allows for the delivery of therapeutics only in cancer cells and removed from normal cells.Small interfering RNA (siRNA) are synthetic antisense oligonucleotides to the mRNA of the gene of interest that works to silence the expression of a particular gene by its complementary binding.