A. Left: Tg(fli1ep:MCP-GFPnls) zebrafish embryo at 26 hours post fertilisation (hpf) displaying vascular-specific expression of MCP-GFPnls. Inset shows the nuclear expression of MCP-GFPnls in the intersomitic vessels (ISVs) sprouting from the dorsal aorta (DA). Middle: scheme depicts the in vivo MS2 system strategy with fli1 enhancer/promoter (fli1ep)-driven expression of reporter constructs, simultaneous translation of Lyn-mCherry reporter and binding of MCP-GFPnls to 24xMS2-rab13 3'UTR. Right: scheme illustrates ISV cells expressing Lyn-mCherry imaged in panels B-D. TC: tip cell; SC: stalk cell. Arrowheads indicate non-nuclear localisation of MCP-GFPnls; arrows indicate direction of ISV sprouting; yellow dashed lines outline ISV (A) 