Arresting supporters: targeting neutrophils in metastasis.

It is becoming increasingly clear that leukocytes dynamically regulate cancer progression and metastasis, and among leukocytes, granulocytic cells abundantly accumulate in metastatic organs; however, their function in metastasis remains controversial. In a recent report in Nature, Wculek and Malanchi clarify the role of mature neutrophils as mediators of metastatic initiation and provide a targeted approach to prevent the pro-metastatic activity of neutrophils in breast cancer models.