In conclusion, in this study we identified the anti-angiogenesis role of antagomir-21 in VEGFR2-luc mouse breast tumor model via noninvasive BLI and disclosed potential mechanism of antagomir-21 in inhibiting angiogenesis via suppressing HIF-1α/VEGF/VEGFR2 signaling pathway. The gene discussed is HIF1A; the disease is breast neoplasm.