In order to investigate the relative contribution of H19 and miR-675 in the metastatic process in vivo, breast cancer cells, stained with liposoluble fluorophores, were injected into the yolk sac of transparent transgenic zebrafish embryos having their entire vascular system labeled with green fluorescence, and the invasion of the injected cells was evaluated three days post-injection, as described in Materials and Methods. Here, H19 is linked to breast cancer.