The RB1 Tumor-Suppressor Gene ____

Question

The RB1 tumor-suppressor gene ____.
A) controls the G2/M checkpoint
B) controls the G1/S checkpoint
C) is overactive in cases of retinoblastoma
D) is overactive in cases of breast cancer
E) is overactive in cases of leukemia

Accepted Answer

The RB1 tumor-suppressor gene controls the G1/S checkpoint, which is where the cell decides whether to proceed with DNA replication or enter a quiescent stage. Mutations or inactivation of RB1 can lead to uncontrolled cell growth and cancer. Additionally, RB1 is underactive in cases of retinoblastoma, not overactive as stated in option C. RB1 can also be underactive in breast cancer and leukemia, so options D and E are incorrect.