Of Snail, mice, and women.

Mechanisms for breast cancer recurrence and metastases are poorly understood. New evidence from a transgenic mouse mammary tumor model suggests that the transcriptional repressor, Snail, may play a role in recurrence by downregulating E-cadherin and inducing an epithelial-to-mesenchymal transition. Preliminary information from expression microarray data sets from primary human breast cancers suggests that high levels of Snail are correlated with poor clinical outcome for women with early breast cancer. The identification of a molecular pathway involved in mammary tumor recurrence in a mouse model offers both opportunity and challenge to confirm, extend, and exploit these findings in the clinic.