BIRC5 and cancer: For instance, survivin expression levels are positively correlated with poor prognosis in human cancer patients, and the activity of the survivin promoter and the effectiveness of Surv.m-CRA were elevated in CSCs, which are more malignant than non-CSC fractions of cancer cells.10,13,14 By contrast, replication of some oncolytic viruses cannot be transcriptionally controlled.