Schematic representation of the functional consequences of DLL4 targeting by miR-30. (A) A zebrafish embryo at 72 hpf is depicted. A section of the intersegmental vessels (ISV) has been enlarged. The dorsal aorta (DA) and posterior cardinal vein (PCV) have also been depicted in red and blue, respectively. The dorsal longitudinal anastomotic vessel (DLAV) is shown in purple. (B) When miR-30 is overexpressed, dll4 is down-regulated and a deregulated network of intersegmental vessels forms as the tip cell phenotype is not restricted and excessive sprouting occurs. (C) When miR-30 regulation of dll4 is blocked using a target protector, dll4 is up-regulated, and consequently kdrl expression is reduced. When combined with kdr knockdown, the restriction of tip cell specification and inhibition of Vegfa signaling which ensues prevents normal intersegmental vessel sprouting and the DLAV does not form.