Extracellular matrix regulates expression of the TGF-beta1 gene

The influence of the extracellular matrix in the expression of transforming growth factor-beta1 (TGF-beta1) by mammary epithelial cells was investigated. The absence of the basement membrane resulted in an upregulation of TGF-beta1 expression when the cells were maintained on a plastic substratum. Genetic analysis showed that the effect was due to enhanced transcription from the TGF-beta1 promoter gene. The basement membrane is thought to be part of a feedback loop that regulates TGF-beta1 expression and basement membrane formation.