Normally functioning cell cycle regulators are molecular signals that do all of the following EXCEPT:     Inhibit progression through the cell cycle     Stimulate progression through the cell cycle     Instruct cells to progress from M phase directly to G2 phase during the cell cycle     Instruct cells to initiate programmed cell death during development     Instruct cells to differentiate during development

The Rb protein has been called the “master brake” of the cell cycle. Describe how the Rb protein acts as a cell cycle brake. How is the brake released in mid- to late G1 to allow the cell to proceed to S phase?

Describe how p53 functions to arrest cells in G1 and G2 stages of the cell cycle to regulate the progression to the S and M stages respectively

Part A and B A. What below would be likely to lead to cancer development? A) Overexpression of a cell cycle checkpoint inhibitor B) Loss of expression of a growth factor that promotes cell cycle entry C) Overexpression of a receptor tyrosine kinase that promotes cell cycle entry D) Overexpression of a DNA damage repair enzyme E) Loss of expression of a regulatory transcription factor that activates transcription of a cyclin   B. Taxols inhibit the proper function of microtubules and are frequently used as chemotherapy drugs. What is the function of microtubules during the cell cycle? A) They promote the G1 to S checkpoint B) They normally inhibit M phase from being completed C) They form the mitotic spindle E) They mediate DNA replication F) They form the cleavage furrow during cytokinesis