Cell cycle checkpoints are an important feature of a dividing cell to reduce errors that can occur in various stages of the cell cycle. Loss of Rb, an important part of the G1-S transition checkpoint, can result in uncontrolled cell cycle progression and cancer. All of the following would mimic loss of Rb except:
- Constitutively active G1-CDK
- Constitutively active ERK
- Constitutively active E2F
- Constitutively active Myc
- Constitutively active Ras GTPase activating protein