QUESTION 21

1. Describe the function of FOS in normal cellsand cancer cells.

   For a complete answer, you will need to include:

   A) its mechanism of action, including other proteins it workswith and its downstream targets

   B) how its activity is regulated

   C) whether it acts as an oncogene or a tumor suppressor and whyinactivation or activation of the gene leads to cancer

   QUESTION 22

2. Signal Transduction:

   A) Explain how growth factors, acting through the signaltransduction pathway, regulate cellproliferation.  Names of specific proteins and theirfunction must be given.

   B) Give 2 specific examples of how an alteration in the signaltransduction pathway can lead to cancer

QUESTION 23

1. Cell Cycle Regulation:

   Describe the mechanism by which the cell cycle is regulated bymitogens. In your answer, be sure to include the following:

   a) The phases of the cell cycle and protein whose concentrationsvary during the cell cycle

   b) The complexes formed by the proteins in (a) and themechanisms by which they are regulated

   c) The substrate of the complexes in (b) and its role in cellcycle control

   d) Describe 2 ways in which the substrate in (c) can beinactivated to cause cancer

QUESTION 24

1. DNA Damage and the cell cycle:

   Describe the mechanism by which DNA damage such as adouble-strand break leads to cell cycle arrest.

   Be sure to include:

   a) how the pathway is regulated

   b) why it is important to regulate the cell cycle duringconditions of DNA damage