FLII and cancer: In addition, angiographic zebrafish models such as the Tg(fli:eGFP) zebrafish line, a transgenic model with GFP-labeled blood vessels, allow for the in vivo study of the interaction between endothelial and cancer cells [44–46] and the use of confocal microscopy opens up many possibilities for the study of single-cell behavior of cancer cells in a complex system [44].