Examination of the role of β1 integrins in mediating microglial adhesion to vitronectin or fibronectin. A. Adhesion to vitronectin or fibronectin of microglia derived from wild-type or β3/β5 integrin DKO mice was examined in the presence of a β1 integrin function-blocking antibody. Adhesion is expressed as the number of cells adherent within a given field of view after 30 minutes of cell adhesion. All points represent the mean ± SEM of three experiments. Note that β1 integrin blockade had no impact on the adhesion of wild-type or β3/β5 integrin DKO microglia to vitronectin, but that it inhibited microglial adhesion to fibronectin by approximately 50% (wild-type) or greater than 80% (DKO). B. Adhesion to fibronectin of microglia derived from wild-type, β3 KO, β5 KO or β3/β5 integrin DKO mice was examined in the presence of a β1 integrin function-blocking antibody. Note that β1 integrin blockade of wild-type or β5 integrin KO microglia resulted in approximately 50% inhibition of adhesion to fibronectin, but in β3 integrin null or DKO microglia, the inhibition was greater than 80%.