Localized and reversible TGFbeta signalling switches breast cancer cells from cohesive to single cell motility.

In vivo imaging of mammary carcinoma cells reveals that activation of a TGFβ-induced transcriptional response induces the motility of individual cells, allowing them to spread through the blood stream. In the absence of TGFβ, cells migrate as groups and can only metastasize through the lymphatic system.