Keratinocyte Growth Supplement-defined (KGS-d) is a medium supplement designed for the optimal growth of normal human keratinocytes in vitro. It is a sterile, concentrated (100X) solution which contains growth factors, hormones, and proteins necessary for the culture of normal human keratinocytes. The supplement is formulated (quantitatively and qualitatively) to provide a defined and optimally balanced growth environment that maximally promotes the growth of normal human keratinocytes in vitro. The supplement is designed as an additive for keratinocyte medium-defined (KM-d, Cat. No. 2111) and should be used in conjunction with that medium.