Mmp15 is a direct target of Snai1 during endothelial to mesenchymal transformation and endocardial cushion development

► Snai1 is required for cell transformation and motility during cushion EMT. ► MMP15 promotes cell motility, but not transformation during cushion EMT. ► MMPs are required for Snai1-mediated cell migration during cushion EMT. ► MMP15 activity rescues cell migration defects in cushions following snai1 knockdown. ► Snai1 binds and regulates E-box rich regions within the mmp15 gene.