TGFbeta primes breast tumor cells for metastasis

The microenvironment of a tumor is known to influence tumor progression and spread to distant sites (metastasis). Padua et al. (2008) now show that transient exposure of breast cancer cells to the signaling molecule transforming growth factor beta (TGFbeta) promotes their extravasation from blood vessels and entry into the lung by upregulation of the adipokine angiopoietin-like 4 (ANGPTL4). Their work shows that the later stages of metastasis can be influenced by transient signals produced in the primary tumor microenvironment.