p44/42 MAP Kinase(Thr202), ERK (extracellular signal regulated kinase), also known as MAPK (mitogen activated protein kinase) has two closely related isoforms of 44 kDa and 42 kDa, respectively. These kinases belong to a family of serine/threonine kinases that are activated upon treatment of cells with a large variety of stimuli including mitogens, hormones, growth factors, cytokines, and bioactive peptides. Cell stimulation induces the activation of a signaling cascade, the downstream effects of which have been linked to the regulation of cell growth and differentiation as well as the cytoskeleton. ERK1 and ERK2 are phosphorylated within the activation loop on both a Threonine and a Tyrosine residue (within a Thr-Glu-Tyr motif) by MEKs (MAPK/ERK kinases), thereby greatly elevating the activity of ERK1&2.
