Fig. 4. Clonal growth of keratinocytes selected for high or low MCSP and ß1 integrin expression. (A) FACS profiles of ß1 integrin and MCSP expression in the four populations of primary human keratinocytes used for the clonogenicity assays in (B). Suprabasal cells were gated out on the basis of forward and side scatter. (B) FACS-sorted keratinocyte populations shown in (A) were plated at clonal density in triplicate onto mitotically inactivated fibroblast feeders and cultured for 10-14 days. The proportion of plated cells that formed clones of any size (%CFE) and the proportion of clones that were abortive, consisting of terminally differentiated cells (%Ab), were determined.