Since then, researchers have been focused on addressing the shortcomings of the original technique, notably its low efficiency<ref>e.g. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3448677/pdf/pone.0045633.pdf</ref> and the tumorigenicity <ref>e.g. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204002/pdf/281_2011_Article_266.pdf</ref> of the resulting iPSCs, and many novel variations of the original method have been published. No current protocol for generating iPSCs is capable of producing cells that perfectly (and reliably) mimic the behavior of ES cells;<ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3457607/pdf/CFG2012-538639.pdf</ref><ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114956/pdf/10815_2011_Article_9552.pdf</ref><ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159104/pdf/ars.2010.3814.pdf</ref> accordingly, techniques for generating iPSCs will remain an area of intense research for the foreseeable future. | Since then, researchers have been focused on addressing the shortcomings of the original technique, notably its low efficiency<ref>e.g. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3448677/pdf/pone.0045633.pdf</ref> and the tumorigenicity <ref>e.g. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3204002/pdf/281_2011_Article_266.pdf</ref> of the resulting iPSCs, and many novel variations of the original method have been published. No current protocol for generating iPSCs is capable of producing cells that perfectly (and reliably) mimic the behavior of ES cells;<ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3457607/pdf/CFG2012-538639.pdf</ref><ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3114956/pdf/10815_2011_Article_9552.pdf</ref><ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3159104/pdf/ars.2010.3814.pdf</ref> accordingly, techniques for generating iPSCs will remain an area of intense research for the foreseeable future. |