Suicide gene therapy has also been proposed in which a therapeutic gene, for example Herpes Simplex Thymidine Kinase or E. Coli purine nucleoside phosphorylase, under the control of promoters for transcription factors exclusively over-expressed in cancer cells such as Ascl1 is expressed and activates Ganciclovir to induce cell cycle arrest [34-36]. This evidence concerns the gene ASCL1 and cancer.