Limited expression of cre recombinase is controlled by its own enzyme activity, as it expression cassette in pTRINA is flanked by lox sites and the nonepisomal nature of the IDLV intermediates switches the expression off. Our genetic approach, Kas/TRINA, could be used to modify refractory cells by increasing the amount of virus or establishing efficient and selective Phenylarsine oxide transduction protocols. This system is affordable, efficient, and easy, and can be applied in large-scale assays or low-to-medium throughput assays. Therefore, we consider that our strategy may be a useful tool for genetic manipulation, not only of tagged cell lines, but also of ESCs and iPSCs. Although similar to the strategies used in other reports, our drug/colored selectable system is a predictable and highly reproducible platform to study gene function in almost any cell type. However, the novelty of delivering recombinase in the same lentiviral vector in a non-integrative and self-limiting manner by means of lox flanking eliminates enzyme toxicity and the need for additional and independent gene transfer. The availability of cell lines tagged at predefined loci with heterospecific lox sites in combination with att or frt sequences should facilitate��through repeated transduction with IDLV encoding different recombinases��the study of multiple genetic elements. The strategy can be Protriptyline hydrochloride further developed using engineered transgenes containing specific recombinase sites and will enable the generation of secondary cells lacking a particular factor and leaving only a localized genetic scar. Our strategy can be applied in the screening of early molecular events leading to stem cell differentiation and disease, in genetic simulation of disease models, and, importantly, in genetic studies using iPSC technology. In addition, the genetic homogeneity of the cells makes chemical and genetic screening approaches feasible, easy, comparable, and reliable. The efficiency and lengthy process of generating knock-in mouse models should be shortened by combining established ES cell lines bearing the docking KAS or KAS-like derivatives with available lentiviral technology for microinjection to generate KI or KD by RMCE. We further demonstrate the powerful technology of viral vectors based on non-integrative lentivirus, an achievement that will contribute to the development of novel and safer strategies for gene transfer.