ERK1/2, phosphorylation Mitogen-activated protein kinase

Inhibits NAD(P)H oxidase cytochrome b558 activity, increases oxidant production by the mitochondria and inhibits ASMC proliferation and phosphorylation of the ERK1/2 mitogen-activated protein kinase and expression of cyclin D1 in human airway smooth muscle [74]... 

There are numerous data that peroxynitrite is involved in cell death and tissue injuries in many clinical conditions. An important mechanism underlying peroxynitrite toxicity is the reaction of tyrosine nitration. Tyrosine nitration inactivates certain enzymes, as was postulated for prostacyclin (PGI2) synthase (M14), cytochrome P450 2B1 (RIO), tyrosine hydroxylase (A 14), and MnSOD (Yl). Moreover, nitration blocks tyrosine phosphorylation, and thus interferes with the tyrosine kinase signaling pathways (K18). The peroxynitrite treatment of rat liver epithelial cells stimulates mitogen-activated protein kinases p38 MAPK, JNK1/2, and ERK1/2 the mechanism of this effect awaits elucidation (S9). 

MAPK proteins, which in turn are activated by different MAP kinase pathways (see Fig. 10.4). Much of the mitogenic effects of ERK signals can be explained by the observation that ERK-induced expression of transcription factors stimulates the transcription of D-type cyclins, which promotes the Gl/S-phase transition in the cell cycle (see Section 13.4.1). Furthermore, phosphorylation of the CTD of RNA polymerase II (see Section 1.4.3.4) has also been reported to be mediated by the ERK1/2 proteins. 

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