KDR and neoplasm: In order to further characterize the potential that tumor cells have to develop new blood vessels and in turn, their ability to invade and form micrometastases, several transgenic lines in which the vasculature is labeled are also available; Tg(fli1:eGFP)y1 [119]; Tg(flk1:eGFP)s843 [120]; Tg(flk1:mCherry) [121].