Another study applied NILVs to treat cancer using a different approach, by turning NILVs into oncolytic viruses: NILVs expressing the diphtheria toxin A, an immunotoxin widely used in cancer treatment, under the control of the survivin promoter, a highly active promoter in tumour cells, were shown to inhibit tumour growth in immunodeficient nude mice [97]. This evidence concerns the gene BIRC5 and cancer.