Cytokines cell signaling inhibitors

Another important family of kinases for drug discovery is the mitogen-activated protein kinases (MAPKs). These are proline-directed serine/threonine kinases that activate their substrates by dual-phosphorylation. MAPK enzymes are activated by a variety of signals including growth factors and cytokines, discussed in chapter 6. The MAPK family plays a critical role in cell cycle progression. Small molecule inhibitors of MAPK may have utility in the treatment of cancer. 

Regulation at the transcription level has also been described for the inhibitor pl5 4b, The cytokine TGPp is involved in this regulation (see Chapter 12). Binding of TGPP to its receptor initiates a signal chain that culminates in activation of transcription of the gene for pl5 b and may lead to a halt in the cell cycle. 

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