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An endogenous small interfering RNA (endo-siRNA) pathway had only previously been characterized in worms. The recent discovery of diverse intramolecular and intermolecular substrates that generate endo-siRNAs in flies and mice raise many questions regarding the biogenesis and function of small regulatory RNAs in animals.
A degradation signal (degron) is a minimal element that is sufficient for the recognition and subsequent degradation of a protein by the proteolytic machinery. Combined structural and functional studies of degrons are essential for understanding how the ubiquitin–proteasome system is usedin vivo.
The roles of Rho GTPases have been extensively studied in several mammalian cell types using different mutants. The availability of knockout mice for several members of the Rho family is now revealing new information about their roles in signalling to the cytoskeleton and in development.
The tumour suppressor p53 integrates incoming stress signals to prevent malignant progression by inducing cell responses such as apoptosis and senescence. The specific response, coordinated by p53 post-translational modifications and the availability of p53 cofactors, determines the appropriate cellular fate.
The retinoblastoma tumour suppressor pRB, the E2F transcription factor and related proteins are conserved in many species of plants and animals. Genetic and biochemical experiments now show that pRB and E2F proteins of worms, flies and mammals share similar core activities and regulatory mechanisms.
Somatic cells can be converted to an embryonic-like state by introducing a defined set of factors. Induced pluripotent stem (iPS) cells raise new hopes for regenerative medicine. What are the hurdles that need to be overcome to take advantage of this technique?
Membrane blebs are considered to be a hallmark of apoptosis; however, blebs are also observed in healthy cells during cytokinesis and cell motility. What are the potential mechanisms by which blebbing can be polarized and translated into movement? And what are the advantages of blebbing motility?
