Craf-1 protein kinase is essential for mouse development

The three mammalian Raf serine/threonine protein kinases mediate the transduction of proliferative and differentiative signals from a variety of cell surface receptors to the nucleus. We report here that Craf-1 is essential for mouse development, as its mutation results in embryonic lethality. Developmental defects are: found in mutant placentas as well as in the skin and in the lungs of mutant embryos. Craf-1 mutants also display a generalized growth retardation which is consistent with the ubiquitous expression of Craf-1 and which could be due to the reduced proliferation of mutant cells. Interestingly, the time-point of embryonal death varies depending on the genetic background. This suggests that Craf-1-mediated signaling is affected by genetic background-specific alleles of other genes. (C) 1998 Elsevier Science Inland Ltd. All rights reserved.