Moreover, in vivo studies also supported that targeted gamma-secretase inhibitors delivery-enhanced tumor penetration and retainment at the tumor site as compared with free drug.152 Recently Lo et al. have designed a small interfering RNA-delivery approach against the enhancer of zeste homolog 2 and Oct-4 genes upregulated in head and neck squamous cell carcinoma using polyurethane-short branch polyethylenimine. This evidence concerns the gene POU5F1 and neoplasm.