Recombinant T2-TrpRS protein delivered to "newborn" retinas potently inhibits new blood vessel formation without affecting already established blood vessels. A superficial layer develops in the first week (panels left) and by 10 to 12 days, a deep retinal vascular layer begins to develop (lower right panel). If T2-TrpRS is adminstered on day seven, the deep vascular layer does not develop (upper right panel), while control protein has no effect (lower right panel). In both cases, the superficial layer develops normally (upper and lower left panels).