Contrary to previous studies by Xu et al. [84,85] in which BMP4 reduced the laser-induced choroidal neovascularization and TNFα-induced inflammatory response in RPE, our data suggested that BMP4 disrupts the RPE and REC barrier function and may play a role in the development of DR and AMD via activating MMPs. The gene discussed is BMP4; the disease is age-related macular degeneration.