MAPK3 and diabetic retinopathy: Regarding diabetic retinopathy, exposure to high glucose decreases H19 levels, and this results in the activation of the mitogen-activated protein kinase-extracellular signal-regulated kinase 1/2 (MAPK-ERK1/2) pathway downstream of transforming growth factor beta (TGFβ) signaling, which in turn promotes EndoMT [86].