Fig. 4. 6 integrin+/MTS24+ keratinocytes form large colonies with high efficiency in culture. Keratinocytes harvested from dorsal epidermis of adult C57Bl/6 mice were analysed by FACS (A,B) or were sorted (C-F) under sterile conditions. (A,B) Flow cytometric analysis of (A) isotype control versus (B) MTS24-labelled keratinocytes indicates that there is a subpopulation of MTS24+ keratinocytes. (C-F) Sorted 6 single+, 6+/MTS24+ or the unseparated mixture (all sorted) keratinocytes were grown for 14 days, fixed in 4% formal saline, and stained with Rhodamine B to visualise colony growth. Data are shown from a representative experiment, which was repeated several times with similar results. (C) FACS selection of keratinocytes. (D) Representative culture dishes with stained colonies. (E,F) Graphs of colony-forming efficiency (E, black bars) and size of colonies (E, white bars; F). Bars represent the mean of at least four replicate culture wells±s.e.m. Asterisks indicate significant differences of 6+/MTS24-relative to 6+/MTS24+ (P<0.05; unpaired two-tailed t test).