The origin of the fibronectin (FN) found in the extracellular matrix of tissues has not been
defined experimentally. Previous studies suggest that there is contribution from both local
tissue production and transfer from plasma, but the extent of this phenomenon has not been
addressed. We have shown before that engineered mice constitutively expressing extra
domain A-containing FN (EDA+ FN) have a significant decrease of FN levels in plasma and
most tissues. We showed that hepatocytes modified to produce EDA+ FN have normal …