Figure 1. a, Immunostaining showed that NG2-positive OPCs (green) in cerebral cortex of postnatal day 2 rat expressed VEGF-receptor 2/KDR/Flk-1 (red). Nuclei were stained with DAPI (blue). b, Immunostaining demonstrated that our OPC cultures expressed VEGF-receptor 2/KDR/Flk-1 (red) as well as OPC markers NG2 (green) and A2B5 (green). Nuclei were stained with DAPI (blue). c, Western blotting confirmed that OPCs expressed Flk-1. The rat brain endothelial cell line RBE.4 (endothelium) was used as a positive control. d, VEGF-A did not affect OPC proliferation in culture. Twenty-four hours after VEGF-A treatment, OPC proliferation was measured by a WST assay. e, VEGF-A did not differentiate OPCs. Twenty-four hours after VEGF-A treatment, cell lysates were subjected to Western blot with anti-myelin-basic protein (MBP; a marker for OPC maturation) and anti-β actin (internal control). Samples from cells differentiated with 10 ng/ml CNTF and 50 ng/ml T3 (C/T) were used as a positive control. f, VEGF-A induced the OPC migration in culture. Twenty-four hours after VEGF-A treatment, migrated OPCs was counted in a blind manner. Representative pictures demonstrated the increase in OPC migration upon VEGF-A treatment (100 ng/ml for 24 h). The dotted line represents the cut and the arrow indicates the direction of OPC movement. Quantitative data showed that VEGF-A migrated OPCs in a concentration-dependent manner. g, VEGF-C promoted the OPC proliferation in culture. Twenty-four hours after VEGF-A (100 ng/ml) or VEGF-C treatment, OPC proliferation was measured by a WST assay. In contrast, VEGF-C showed less efficacy than VEGF-A in the OPC migration in culture. Twenty-four hours after VEGF-A (100 ng/ml) or VEGF-C (100 ng/ml) treatment, migrated OPCs was counted in a blind manner. *p < 0.05 versus VEGF-A.