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The extracellular signals which regulate the myogenic program are transduced to the nucleus by mitogen-activated protein kinases (MAPKs). We have investigated the role of two MAPKs, p38 and extracellular signal-regulated kinase (ERK), whose activities undergo significant changes during muscle differentiation. p38 is rapidly activated in myocytes induced to(More)
Cells were microinjected with four mouse monoclonal antibodies that were directed against either alpha- or beta-tubulin subunits, one monoclonal with activity against both subunits, and a guinea pig polyclonal antibody with activity directed against both subunits, to determine the effects on the distribution of cytoplasmic microtubules and 10-nm filaments.(More)
Expression of the ras oncogene is thought to be one of the contributing events in the initiation of certain types of human cancer. To determine the cellular activities that are directly triggered by ras proteins, the early consequences of microinjection of the human H-ras proteins into quiescent rat embryo fibroblasts were investigated. Within 30 minutes to(More)
We have examined the mechanism by which the transcriptional activity of the cAMP-responsive factor CREB is attenuated following induction with forskolin. Metabolic labeling studies reveal that, after an initial burst of phosphorylation in response to cAMP, CREB is dephosphorylated and transcription of the cAMP-responsive somatostatin gene is correspondingly(More)
The innate immune response plays a crucial role in satisfactory host resolution of bacterial infection. In response to chemotactic signals, neutrophils are early responding cells that migrate in large numbers to sites of infection. The recent discovery of secreted neutrophil extracellular traps (NETs) composed of DNA and histones opened a novel dimension in(More)
Microinjection of the purified catalytic subunit of the cAMP-dependent protein kinase (A-kinase) into living rat embryo fibroblasts leads to dramatic changes in vimentin intermediate filament (IF) organization, involving the collapse of the filaments into tight bundles. In some cell types, this rearrangement of the IF proceeds further, leading to an(More)
Human mutations in Nkx2-5 lead to progressive cardiomyopathy and conduction defects via unknown mechanisms. To define these pathways, we generated mice with a ventricular-restricted knockout of Nkx2-5, which display no structural defects but have progressive complete heart block, and massive trabecular muscle overgrowth found in some patients with Nkx2-5(More)
To investigate the possible role of ras proteins in the differentiation process signaled by nerve growth factor, we have microinjected the proto-oncogenic and oncogenic (T24) forms of the human H-ras protein into living rat pheochromocytoma cells (PC12). PC12 cells, which have the phenotype of replicating chromaffin-like cells under normal growth(More)
The Golgi apparatus is a dynamic organelle whose structure is sensitive to vesicular traffic and to cell cycle control. We have examined the potential role for rab1a, a GTPase previously associated with ER to Golgi and intra-Golgi transport, in the formation and maintenance of Golgi structure. Bacterially expressed, recombinant rab1a protein was(More)