Fig. 2. Loss of ß1-integrin surface expression of neurosphere-derived cells, confirmed by FACS analysis using a FITC-conjugated anti-ß1-integrin antibody, reduces adhesion to fibronectin and laminin substrates. (A) Histogram of unlabelled wild-type neurospheres used as controls. (B) Histogram of non-infected, non-recombined neurospheres carrying the intact conditional ß1-integrin allele showing ß1-integrin surface expression (arrow). (C) Histogram of adeno Cre infected, recombined neurospheres demonstrating that the removal of the conditional ß1-integrin allele leads to cell surface loss of ß1-integrin expression (arrow). Two passages were needed for this dramatic reduction of ß1-integrin expression (D-E). Absence of ß1-integrin cell surface expression leads to reduced ß1 integrin-mediated short term adhesion of mutant cells (triangles) compared with control cells (diamonds) on both laminin-1 (LM1, D) and fibronectin (FN, E) substrates. (D) A significantly reduced adhesion (***P<0.001) was found on laminin-1 at all time points investigated compared with adherence of control cells. (E) On fibronectin a significant reduction in adhesion (***P<0.001) was found at 30 and 60 minutes after plating compared with that in control cells at the same time points. The y-axis represents the percentage of adherent cells compared with adherent cells on PDL-coated sister plates at the specific time points. Results are the mean±s.d. of three experiments.