Our finding of differential expression of BMP4 in geographicatrophy and neovascular AMD and the interactive roles of oxidative stress,inflammation and senescence in the regulation and functional effects of thisgrowth factor, suggests the possibility that BMP4 may be playing a part in themolecular switch determining which phenotypic pathway is taken in theprogression of AMD. Here, BMP4 is linked to age-related macular degeneration.