Outside-in integrin signalling in oligodendrocytes. Panel A shows that morphological differentiation of oligodendrocytes on laminin-2 requires integrins. A monoclonal anti-β1 integrin-blocking antibody (Ha2/5) inhibits oligodendrocyte process formation on laminin-2 (Ln) but not fibronectin (Fn). In contrast, RGD peptides that block αV integrins inhibit the morphological differentiation on Fn. No change is seen with control RAD peptides that do not perturb integrin function. Panel B shows that integrin activation by outside-in signalling promotes differentiation. Increasing laminin-2 concentrations are associated with greater process complexity and myelin sheet formation, with significant increases seen between 1 and 10 μg/ml. Mn2+ (Mn) also promotes differentiation, with significant effects seen at the lowest laminin-2 concentration (0.1 μg/ml). Note that the addition of Mn2+ has no significant effect on morphology at the higher laminin concentrations. Single and double asterix indicate significance levels of p < 0.05 and p < 0.01 respectively, calculated using Student's paired t-test. Scale bar in panel A is 20 μm.