MMP9 and choroidal neovascularization: For example, Xu et al. [59] tested the effect of BMP4 on MMP9 secretion in primary RPE cells isolated from fetal eyes after activation with TNF-α and linked this to the ability of BMP4 to inhibit choroidal neovascularization (CNV) in the experimental mouse model of laser-induced CNV using transgenic mice over-expressing BMP4.