Rat Epidermal Keratinocytes (REK) are derived from the skin of normal Sprague Dawley rats. They are cryopreserved at the end of primary culture. These epithelial cells proliferate well when thawed and plated from cryopreservation, but they do not plate and proliferate after trypsinization

REK was found to maintain the ability to differentiate in vitro, similar to that of the basal keratinocytes in the epidermis¹. The effects of thrombin and TP508 on wound healing were demonstrated by using rat dermal excision². Choline is essential for acetylcholine biosynthesis and is involved in cell signaling. It requires a transporter to enter the cell. The presence of choline transporter 1 in nerve fibers and epithelial cells suggest its pivotal role³. REK was suggested as a useful model for the study of P450-catalysed metabolism of xenobiotics in skin⁴.