ETV2 and breast cancer: Let‐7a was shown to control Etv2 (Ets‐variant protein 2) expression and EC differentiation through a post‐transcriptional mechanism in zebrafish.40 Our in vivo and in vitro data were consistent with the previous study's conclusions that let‐7a imposed anti‐angiogenesis activity in a mouse model of breast cancer.19, 41 In particular, multiple evidence suggest let‐7a suppress cancer cell migration, invasion and proliferation.