By the same token, zinc-finger-based artificial transcription factors, which can modify the epi-transcriptional state of endogenous promoters with single locus specificity [9, 10], have been employed to reduce SOX2 mRNA and protein via targeting of proximal SOX2 promoters in cultured cancer cells and xenografts [7, 11], but their poor in vivo delivery to solid tumor tissue limits their usefulness for stable SOX2 down-regulation in a clinical context. Here, SOX2 is linked to cancer.