Fig. 2. Effect of ß1 integrin deletion on adhesion of primary keratinocytes. (A-C) Surface expression of integrins in freshly isolated keratinocytes from 2-day-old K5ß1-null mice (ß1 /) and control littermates that were homozygous for the floxed ß1 integrin allele but did not express Cre recombinase (ß1 fl/fl), as determined by FACS analysis. Orange lines represent the second antibody control. Keratinocytes were stained with antibodies against ß1, ß4 and v integrins. (D,E) Loss of focal adhesions and actin stress fibres in ß1-null keratinocytes. Wild-type (D) and ß1-deficient (E) keratinocytes were cultured for 2 days and examined for focal adhesions (green) and F-actin (red) by immunofluorescence staining with an antibody against paxillin or by staining with phalloidin, respectively. Note that the ß1-null cells are completely rounded and that the green fluorescence is cytoplasmic paxillin. (F) Adhesion of wild-type and ß1-deficient keratinocytes. Keratinocytes were plated onto 96-well plates (5x10⁴ cells/well), pre-coated with fibronectin (FN), laminin (LN), poly-D-lysine (PDL), collagen type I (COLL 1) and collagen type IV (COLL 4). Adhesion was quantified using a CytoTox 96 colorimetric kit. Error bars represent standard deviation of the mean of triplicate samples within one experiment.