Evaluate each of the following defects. Which could lead to uncontrolled growth in cancer? Select True or False for each statement.T/FThe overexpression of MPF activity.T/FA nonfunctional Rb protein.T/FThe overexpression of G1 cyclin.T/FA nonfunctional E2F protein.

Verified step by step guidance

1. Understand the role of MPF (Maturation Promoting Factor) in the cell cycle. MPF is crucial for the transition from G2 phase to M phase. Overexpression could lead to premature or uncontrolled cell division.
2. Examine the function of the Rb (Retinoblastoma) protein. Rb is a tumor suppressor that regulates the cell cycle by inhibiting E2F. A nonfunctional Rb protein could fail to control cell cycle progression, leading to uncontrolled growth.
3. Consider the role of G1 cyclin in the cell cycle. G1 cyclins are involved in the regulation of the cell cycle at the G1 phase. Overexpression can lead to excessive progression through the cell cycle, potentially causing uncontrolled growth.
4. Analyze the function of E2F protein. E2F is a transcription factor that, when activated, promotes the expression of genes necessary for S phase entry. A nonfunctional E2F protein would likely inhibit cell cycle progression, not promote uncontrolled growth.
5. Evaluate each defect based on its potential to disrupt normal cell cycle regulation and contribute to cancerous growth.

Key Concepts

MPF Activity

MPF, or M-phase promoting factor, is a complex that drives the cell cycle from G2 phase to mitosis. Overexpression of MPF activity can lead to premature or uncontrolled cell division, which is a hallmark of cancer. Understanding its regulation is crucial for identifying potential cancerous growth.

Rb Protein

The retinoblastoma (Rb) protein is a key regulator of the cell cycle, specifically controlling the transition from G1 to S phase. A nonfunctional Rb protein fails to inhibit cell cycle progression, allowing cells to proliferate uncontrollably, which can contribute to tumorigenesis.

G1 Cyclin and E2F Protein

G1 cyclins are proteins that promote the progression of cells through the G1 phase of the cell cycle. E2F proteins are transcription factors that, when activated, lead to the expression of genes necessary for S phase entry. Overexpression of G1 cyclins or a nonfunctional E2F can disrupt normal cell cycle regulation, leading to uncontrolled cell growth associated with cancer.