Millward TA Zolnierowicz S Hemmings BA 1999 Many protein kinases themselves are regulated by reversible phosphorylation. Upon cell stimulation, specific kinases are transiently phosphorylated and activated. Several of these protein kinases are substrates for protein phosphatase 2A (PP2A), and PP2A appears to be the major kinase phosphatase in eukaryotic cells that downregulates activated protein kinases. This idea is substantiated by the observation that some viral proteins and naturally occurring toxins target PP2A and modulate its activity. There is increasing evidence that PP2A activity is regulated by extracellular signals and during the cell cycle. Thus, PP2A is likely to play an important role in determining the activation kinetics of protein kinase cascades. https://sonar.ch/global/documents/4761 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/s0968-0004(99)01375-4 info:eu-repo/semantics/altIdentifier/pmid/10322434 Trends in biochemical sciences. - 1999 Calcium-Calmodulin-Dependent Protein Kinases Cell Cycle Proteins Cyclin-Dependent Kinases Dual Specificity Phosphatase 1 I-kappa B Kinase Immediate-Early Proteins Phosphoprotein Phosphatases Protein Kinase C Protein Kinases Protein Phosphatase 1 Protein Phosphatase 2 Protein Tyrosine Phosphatases Protein-Serine-Threonine Kinases Proto-Oncogene Proteins Proto-Oncogene Proteins c-akt Regulation of protein kinase cascades by protein phosphatase 2A. http://purl.org/coar/resource_type/c_6501