One of the major limitations of using cultured keratinocytes for research studies is that primary keratinocytes senesce after a few passages. Keratinocytes from specific anatomical sites are also difficult to culture. Scientists at the NIH have demonstrated that primary keratinocytes, from several anatomical sites, when treated with a small-molecule inhibitor of the ROCK protein maintain a proliferative state and become immortal without genetic modification to the cells. Keratinocytes are also the host cells for human papillomaviruses (HPVs) and other viruses and this technology enables the study of those viruses that do not immortalize cells. In addition, this technology may enhance the quantity of material available for skin grafts, as current grafting techniques are limited by the amount of donor material immediately available. Thus, this technology may provide an ideal model environment for producing large quantities of both normal and diseased primary human keratinocytes from small numbers of primary cells from individual hosts or anatomical sites for research purposes, testing of therapeutics, skin graft generation and HPV investigation.