Slug (SNAI2) is a widely expressed transcriptional repressor and member of the Snail family of zinc finger transcription factors (1). Similar to the related Snail protein, Slug binds to the E-cadherin promoter region to repress transcription during development (2). The binding of Slug to integrin promoter sequences represses integrin expression and results in reduced cell adhesion (3). Down regulation of E-cadherin expression occurs during the epithelial-mesenchymal transition during embryonic development, a process also exploited by invasive cancer cells (4,5). The tumor suppressor protein p53 induces Slug expression in γ-irradiated cells; Slug protects damaged cells from apoptosis by repressing p53-induced transcription of the proapoptotic Bcl-2 family protein Puma (6). Deletion mutations in the corresponding Slug gene are associated with the pigmentation disorders Waardenburg Syndrome and Piebaldism, while a genetic duplication resulting in Slug overexpression is associated with a collection of congenital heart defects termed tetralogy of Fallot (7).
