Polyak et al. (Reports, 7 March 2008, p. 1377) reported speleothem data leading to their inference that the western Grand Canyon incised much earlier than previously thought. This contradicts several lines of published geological knowledge in the region, hinges upon unjustified hydrogeological assumptions, and is based on two anomalous data points for which we offer alternative explanations.

Fas (CD95) mediates apoptosis of many cell types, but the susceptibility of cells to killing by Fas ligand and anti-Fas antibodies is highly variable. Jurkat T cells lacking CD47 (integrin-associated protein) are relatively resistant to Fas-mediated death but are efficiently killed by Fas ligand or anti-Fas IgM (CH11) upon expression of CD47. Lack of CD47 impairs events downstream of Fas activa...

Tissue-specific expression of Fas-ligand (Fas-L) can provide immune privilege by inducing apoptosis of "invading" lymphocytes expressing Fas. However, accelerated diabetes has been reported in transgenic mice expressing Fas-L in islets (RIP-Fas-L) as a result of Fas-dependent fratricide of beta-cells after transfer of diabetogenic clones. Here we studied whether Fas-L could protect islets from ...

Fas/APO-1 is a cell surface protein known to trigger apoptosis in a variety of cell types upon specific antibody binding. Although extensively studied on normal and malignant hematopoietic cells, little is known about Fas/APO-1 on nonhematopoietic cells. In the study presented here, we have examined Fas/APO-1 expression and function on 11 human tumors of nonhematopoietic origin. By flow cytomet...

This study aimed to describe the multivariate structure of Semimembranosus muscle and backfat fatty acid (FA) composition in 798 Italian Large White heavy pigs investigate effects environmental factors carcass characteristics on FA variations. The total variability was characterized by a negative correlation between saturated polyunsaturated FAs, which strongly depended adiposity. Slaughtering ...

This issue's Cell Biology Select highlights recent studies that improve our understanding of how switches and tuners regulate cellular processes. Two studies encompassing very different processes—programmed cell death and plant lateral root formation—both reveal regulatory switches that work independently of enzyme action. Three other studies present new insights into how cell motility, signal ...

A deadly receptor reveals a benevolent side in a study on page 575. Landau and colleagues show that the cell death–inducing receptor Fas is required for protection against neurodegeneration in a mouse model of Parkinson’s disease (PD). The Fas receptor (Fas), best known for its apoptotic role in the immune system, is widely expressed in nonimmune tissues, including the central nervous system. I...

The Fas Ag is a newly defined cell-surface molecule that may mediate apoptosis. The antibody against Fas Ag can induce the apoptotic cell death in cell lines expressing this Ag. PBL subpopulations at various ages were here examined for Fas expression by two-or three-color flow-cytometric analyses using anti-Fas mAb. It was found that Fas Ag was appreciably detected on a proportion of T and B ce...

BACKGROUND The transmembrane receptor Fas, together with its protein-binding partner (Fas ligand), is a key regulator of programmed cell death (i.e., apoptosis). Fas and Fas ligand also influence the ability of cytotoxic T lymphocytes and natural killer cells to eliminate tumor cells. However, by inducing apoptosis in activated T cells, the Fas/Fas ligand system may protect some tumor cells fro...