What are cell cycle regulators?

Cell cycle regulators are crucial components in the control and progression of the cell cycle, which is the series of phases that a cell goes through as it grows and divides. These regulators primarily function as proteins that can stimulate or inhibit the various stages of the cell cycle. They ensure that cells divide at the appropriate time and under the right conditions, thus maintaining cellular integrity and function.

Some cell cycle regulators include cyclins and cyclin-dependent kinases (CDKs). Cyclins activate CDKs, which then phosphorylate target proteins to trigger progression through the cell cycle. Conversely, certain proteins act as checkpoints that can halt the cycle if there are signs of damage or other issues, preventing unhealthy cell division.

This dynamic regulation is essential for normal cellular function and development, as well as for preventing uncontrolled growth that can lead to cancer. Therefore, the correct answer highlights the dual role of these proteins in both promoting and inhibiting progression through the cell cycle, reflecting their complex and vital role in cellular regulation.