Establishment of cell lines from mouse embryos with early embryonic lethality

It is often difficult to determine molecular mechanisms leading to early embryonic lethality of genetically modified mice due to lack of cells for further analyses. The authors describe here establishment of mouse embryonic fibroblast (MEF) cell lines from gastrulation stage embryos. In this example, using a combination of in vivo and in vitro techniques, the authors successfully generated MEF cell lines that lack both fibronectin (FN) and focal adhesion kinase (FAK).