A cell line has two mutations. One mutation is in the promoter region of Cyclin
ID: 102207 • Letter: A
Question
A cell line has two mutations. One mutation is in the promoter region of Cyclin D that prevents binding of ETS transcription factors. The second mutation is in Retinoblastoma protein (Rb), where the serine residues are replaced by Aspartic acid (Phosphomimetic mutation: a mutation that resembles a phosphorylated protein).
Choose the statement that best describes the cell cycle phenotype of this cell line
The cells are stalled at G1 phase without Cyclin D expression, even though E2F is not bound to Rb.Explanation / Answer
A) the cells are stalled at G1 phase without cyclin D expression, even though E2F is not bound to rb because the ETS are not bound to promoter and cyclin D is not synthesized.
B is wrong because as ETS factors are not bound to the cycling D promoter the cyclin D is not formed and cell cycle can't progress and without cyclin D the cell can't be a cancerous cell.
C is wrong because cell can't do normal cell cycle without cyclin D even if the E2F is not bound to Rb.
D is wrong because cyclin D production starts during the G 1 phase not before the G1 phase, so to enter G1 phase cyclin D is not necessary for entry in S phase cyclin D is necessary.
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