sentences:  Survivin's role in cancer development in the context of a signaling pathway is its ability to inhibit activation of downstream caspase-3 and -7 from apoptosis inducing stimuli.The overexpression of survivin in tumors may serve to increase the tumors resistance to apoptosis and, thus, contribute to cell immortality even in the presence of death stimuli.In this experiment, the oligonucleotide 4003 that targets nucleotides 232-251 of survivin mRNA was found to be the most effective at down-regulating the levels of survivin mRNA in the A549 tumour line.