Using the attached pathway, please answer the following questions: A) Ras protei

Question

Using the attached pathway, please answer the following questions:

A) Ras proteins are known to have mutations in the intrinsic GTPase activity leading to the inability to hydrolyze GTP to GDP. For a cell with this mutation, what would the effect be on cellular proliferation compared to a wild-type control cell that has been treated with EGF – increase, decrease, or no change? Explain your answer.

B) A deletion of the sequence that corresponds to the kinase domain of MEK will lead to a loss of kinase activity in MEK. For a cell with a mutated MEK protein (loss of kinase activity) what would the effect be on cellular proliferation compared to a wild-type control cell that has been treated with EGF – increase, decrease, or no change? Explain your answer.

C) In certain types of cancer the EGFR receptor is known to be overexpressed in tumor cells. Based on the pathway discussed above, how does this overexpression lead to tumor growth.

Explanation / Answer

A). Mutations in the GTAase activity decrease the cellular proliferation because Raf and subsequent proteins cannot be activated.

B). The cellular proliferation decreases in a cell with a mutated MEK protein (loss of kinase activity) what would the effect be on cellular proliferation compared to a wild-type control cell that has been treated with EGF. This is because ERK phosphorylation does not occur, which cause no transcription.

C). Over expression of EGFRs (endothelial growth factor receptors) causes activation of Ras/Raf/Mek pathway and thus, causes increased cell proliferation.

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