Figure 4

Upregulation of erythropoietin and vascular endothelial growth factor in the PDR murine model. Quantitative PCR of erythropoietin (EPO) showed an upregulation of EPO in the Chx10-cre; Vhl^flox/flox mutant mouse retinas compared with Vhl^flox/flox control mouse retinas at 1 week of age, during the onset of neovascularization and the PDR disease phenotype (a). The upregulation of EPO continued through 1 month of age, when hemorrhaging and retinal detachment can be found in this mouse model (a). Vascular endothelial growth factor (Vegf) was highly upregulated in the Chx10-cre; Vhl^flox/flox mouse retinas at the onset of disease (1 week of age), but became comparable to the control Vhl^flox/flox mouse retinas by 1 month of age (b). von Hippel Lindau tumor suppressor protein (Vhl) was reduced in the mutant Chx10-cre; Vhl^flox/flox mouse retinas compared with the control Vhl^flox/flox mouse retinas at all time points analyzed as would be expected with the expression of cre (c). N⩾4 for each group at each time point. Error bars show s.d.’s. *P<0.01.