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4 Cards in this Set
- Front
- Back
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What is ErbB? What is its function?
What is another name for ErbB? |
A receptor tyrosine kinase family consisting of 4 groups. ErbB 1-4.
Functions to mediate a signaling cascade that leads to proliferation, growth and survival. Her1-4 Also, ErbB1/Her1 is also called EGFR (Epidermal Growth Factor Receptor) |
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Describe the two major pathways activated via EGF ligand binding and what they lead to.
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The MAPKinase pathway involves RAS protein and leads to cell proliferation and growth
The other pathway involves PIP3 and ATK and leads to cell survival. |
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Describe the activation of ErrB tyrosine kinase and how ligand binding leads to downstream signaling.
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Ligand binding causes receptor dimerization.
This activates the intracellular kinase domain The intracellular kinase domain then phosphorylates tyrosine residues. (Transautophosphorylation) These phosphorylated tyrosines then recruit molecules that relay the signal downstream. |
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PI3K (lipid kinase) stimulates cell survival converting PIP2 to PIP3
Pten reverses the action of PI3K converting PIP3 to PIP2. Normal cells have functional Pten , but in cancer cells it is mutational and dysfunctional. This is a very common mutation. |
Pathologists will grade tumor biopsies from 0 to 3+ based on the level of EGFR expression. Patients with 2+ and 3+ are eligible for anti-EGF therapy.
Survival time for patients is lower in patients high grade EGFR. |
