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Protein Kinases in the Cell Cycle

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As cells frequently divide to replace dead and damaged cells, checkpoints and regulatory cyclin-dependent enzymes in the cell cycle work to destroy cancer cells (see Figure 1). While kinase enzymes help healthy cells divide, kinase inhibitors block cell division of damaged cells. The Aurora and PCNA kinase inhibitors, in particular, trigger apoptosis at different parts of the cell cycle, in coordination with other inhibitors and specific tumor-suppressing proteins.

Cell Cycle in Cancer. Digital image. Cyclecel. Cyclacel Pharmaceuticals, Inc., n.d. Web.

Figure 1: The Cell Cycle

Another kinase inhibitor, SD-208, was found to arrest the cell cycle at the G2/M checkpoint. Figure 2 shows the cell count for control and SD-208 treated cells during a five-day period.

Tandon, Manuj, et al. "SD-208, a novel protein kinase D inhibitor, blocks prostate cancer cell proliferation and tumor growth in vivo by inducing G2/M cell cycle arrest." PloS one 10.3 (2015): e0119346.

Figure 2: Effect of SD-208 on cell division

Based on the information in Figures 1 and 2, what is the primary role of protein kinases in the cell cycle?

A

Trigger apoptosis of cancerous cells.

B

Arrest the cycle at the G2/M phase.

C

Facilitate cell division and growth.

D

Maintain DNA error checks.