SUCNR1 and Hyperglycemia: It has been shown recently that during hyperglycemia increase in succinate levels acts through GPR91 to trigger VEGF release in retinal ganglion cells by signaling extracellular signal-regulated kinase 1/2 (ERK1/2), p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK)33,71.