Importantly, using the specific 12G10 antibody, strong β1-integrin activation was observed in the mammary tumors derived from shCtrl-3 cells, notably at the peritumoral area, but was absent in shA8-20 tumors and in the contralateral mammary glands of shCtrl mice (Fig 6I), consistent with the hypothesis that ADAM8 promotes tumor cell adhesion onto the endothelium and dissemination via β1-integrin activation in vivo. This evidence concerns the gene ADAM8 and breast cancer.