KDR and diabetic retinopathy: Interestingly, conditional knockout studies suggest that VEGFR2 signalling in RGCs is not required for retinal morphogenesis (Okabe et al., 2014), while VEGFR2 is instead required for the survival of Muller glia, which are in turn essential for the viability of adult retinal neurons in a model of diabetic retinopathy (Fu et al.