Fig. 6. Enhancement of survival by laminin requires ß1-integrins, but not dystroglycan. (A) Indirect immunofluorescent TUNEL to detect cell death in oligodendrocytes transfected with control (ctrl) or dystroglycan (DG) siRNA. Bar graph depicts the average percentage of TUNEL-positive cells relative to total cell population (no significant difference, n=3, error bars represent s.d.). (B) Oligodendrocyte progenitors were differentiated on poly-D-lysine (PDL) or laminin for 4 days with increasing amounts of soluble growth factor PDGF. Integrin- and dystroglycan-blocking antibodies, or control antibodies, at 10 µg/ml were added as indicated. Survival was evaluated using TUNEL on the GalC-positive cell population (newly formed oligodendrocytes). Laminin caused a significant shift in the PDGF dose-response such that survival was increased in response to 0.1 and 1.0 ng/ml PDGF compared with cells grown on PDL (^**P<0.01, error bars represent s.d.). Antibodies against ß1-integrin, but not dystroglycan, blocked the ability of laminin to amplify PDGF-mediated survival at all concentrations (^**P<0.01, error bars represent s.d.).