FLI1 and cancer: Because of the transparency of zebrafish embryos/larvae and the feasibility of observing angiogenesis in live imaging by using Tg(fli1:EGFP) transgenic zebrafish, to date, many cancer xenotransplantation zebrafish models have been reported for tumor-associated angiogenesis studies and for high-throughput drug screenings49, 50, 51, 52, 53, 54, 55.