Presapogenin-CP4 Alternatively, low level activation of caspase-8 may contribute to Peucedanol aberrant cell growth, since activation of the extrinsic death pathway at levels which do not induce apoptosis can foster NF-kB signaling. Since caspase-8 maturation occurs concomitant with the accumulation of DEDs, DED accumulation may act to oppose NF-kB signaling, functioning as a tumor suppressor via their microtubule-associated function. Given the caveats of the studies performed here, it would appear that the DEDs have a better stability than the catalytic domain, which is a target of RING protein-mediated clearance. In summary, we describe a novel function for caspase-8 as an orchestrator of not only apoptosis but also differentiation and senescence. The function is unexpectedly associated with the amino-terminal death effector domains, and does not require caspase-8 catalytic activity. The ermerging roles of this multifunctional protein, and its surprising interactions at the nexus of the cellular migration, proliferation, differentiation and apoptosis pathways, continue to offer key insights into the signaling crosstalk that regulates cell fate. Among the nine monosaccharides that are used as building blocks for mammalian glycans, sialic acid is special. First, it is a key determinant of numerous glycan-receptor interactions involved in cell interaction and communication processes pertinent to health and disease. Second, it is present in the free oligosaccharide fraction of most if not all mammalian milks at levels that vary with species and time of lactation. Sia is thus amongst the first compounds ingested by the suckling newborn and this raises the question of whether or not milk Sia serves as a nutrient. All mammals have the synthetic machinery for de novo synthesis of Sia, which begins with either fructose-6P and glutamine or Nacetylglucosamine and requires a series of enzymatic reactions. The rate limiting step is catalysed by GNE. While the synthetic machinery is present in many organs it is not clear if it is ubiquitous. In addition the absolute expression and/or activity of each gene product can vary per tissue or cell type.