In the absence of Wnt,

TCF is associated with transcriptional repressor proteins Groucho (Gro) that inhibit gene transcription in nucleus

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In humans, there are three RAS, three Raf, two MEK, and two MAP proteins.

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Mammalian MAP kinases include  Jun N-terminal kinases and p38 kinases, which are activated by signaling pathways in response to various types of stresses

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Phosphorylation by MEK at Y-185 and T-183 in activation loop of MAP kinase leads to a marked conformational change & promotes MAP kinase activation and dimerization.

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Activated dimeric MAP kinase induces transcription of the c-fos gene by directly activating TCF, and indirectly activating SRF.

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Feedback regulation by MAP Kinase

activated MAP kinase phosphorylates the HER1 on a threonine residue near the juxtamembrane domain.