Cell Signaling Technology

Product Pathways - MAPK Signaling

Phospho-MEK1/2 (Ser217/221) Antibody #9121

Applications Reactivity Sensitivity MW (kDa) Source
W IP H M R Mk Endogenous 45 Rabbit

Applications Key:  W=Western Blotting  IP=Immunoprecipitation
Reactivity Key:  H=Human  M=Mouse  R=Rat  Mk=Monkey
Species cross-reactivity is determined by Western blot.

Specificity / Sensitivity

Phospho-MEK1/2 (Ser217/221) Antibody detects endogenous levels of MEK1/2 only when activated by phosphorylation at Ser217/221. This antibody does not cross-react with related kinases including activated SEK (MKK4), MKK3 or MKK6. It will also react with MEK1/2 singly phosphorylated at Ser217 and singly phosphorylated at Ser221.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic phospho-peptide (KLH coupled) corresponding to residues around Ser217/221 of human MEK1/2. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from untreated, TPA-treated or lambda phosphatase-treated HeLa cells, using Phospho-MEK 1/2 (Ser217/221) Antibody #9121 (upper) or MEK 1/2 Antibody #9122 (lower).

Background

MEK1 and MEK2, also called MAPK or Erk kinases, are dual-specificity protein kinases that function in a mitogen activated protein kinase cascade controlling cell growth and differentiation (1-3). Activation of MEK1 and MEK2 occurs through phosphorylation of two serine residues at positions 217 and 221 (in the activation loop of subdomain VIII) by Raf-like molecules. MEK1/2 is activated by a wide variety of growth factors and cytokines and also by membrane depolarization and calcium influx (1-4). Constitutively active forms of MEK1/2 are sufficient for the transformation of NIH/3T3 cells or the differentiation of PC12 cells (4). MEK activates p44 and p42 MAP kinase by phosphorylating both threonine and tyrosine residues at sites located within the activation loop of kinase subdomain VIII.

CST's Phospho- MEK1/2 (Ser217/221) Antibody selectively recognizes active MEK, i.e., only when phosphorylated at Ser217/221, and hence is an excellent marker of MEK1/2 activity.

  1. Crews, C.M. et al. (1992) Science 258, 478-480.
  2. Alessi, D.R. et al. (1994) EMBO J. 13, 1610-1619.
  3. Rosen, L.B. et al. (1994) Neuron 12, 1207-1221.
  4. Cowley, S. et al. (1994) Cell 77, 841-852.

Application References

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Companion Products

This product is for in vitro research use only and is not intended for use in humans or animals. This product is not intended for use as therapeutic or in diagnostic procedures.

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