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'Knockin' mice expressing a mutant cytochrome c (Cyt c) (KA allele) is generated, which retains normal electron transfer function but fails to activate apoptotic protease-activating factor 1 (Apaf-1). Studies indicate the existence of a Cyt c- and apoptosome-independent but Apaf-1-dependent mechanism(s) for caspase activation.

A study finds that the C2 domain of PKCdelta directly binds to phosphotyrosine peptides in a sequence-specific manner. The crystal structure of the PKCdelta C2 domain in complex with an optimal phosphopeptide shows a new mode of phosphotyrosine binding in which the phosphotyrosine moiety forms a ring-stacking interaction with a histidine residue of the C2 domain.

The mucosa-associated lymphoid tissue protein Bcl10, containing an N-terminal caspase recruitment domain, regulates lymphocyte proliferation, connecting antigen receptor signaling in B and T lymphocytes to NF-kappaB activation. Data point out that Bcl10 is also involved in neural tube closure.

Apaf1 is a key element in the mitochondrial pathways of programmed cell death induced in response to a wide range of apoptotic stimuli. However, Fas-mediated programmed cell death in thymocytes and activated T cells is not linked with Apaf1. It has not been possible to prove a link between Casp2 and Apaf1, but Casp2 could also be a downstream effector of Apaf1. It appears that other CED-4/Apaf1-like molecules exist. Research on this subject may give more information about mitochondrial pathways of programmed cell death.

The apoptosis of cells is necessary during development to establish normal organ size and architecture. The caspase cascade is an important component of the cell death machinery. Investigations of the requirement of various mammalian cells for two components of these cascade, caspase 9 (Casp9) and caspase 3 (Casp3) revealed that there are four cellular death pathways wherein the requirements for Casp9 and Casp3 differ.