APOE and endothelial dysfunction: As a complementary approach to evaluate a potential endothelial dysfunction in response to diabetes, the expression of VCAM-1, ICAM-1, P-selectin and E-selectin mRNA was measured in intact retinas of wt, ApoE−/−, TNFα−/− and ApoE−/−/TNFα−/− mice by real time RT-PCR.