Final answer:
Growth factors would increase cyclin levels.
Step-by-step explanation:
Cyclins are proteins that play a crucial role in regulating the cell cycle, the process by which a cell grows, replicates its DNA, and divides into two daughter cells. Cyclins undergo periodic fluctuations in concentration during the different phases of the cell cycle, and their levels are tightly regulated to ensure proper cell cycle progression.
Growth factors would increase cyclin levels. Growth factors are signals that promote cell growth and division. When growth factors bind to cell-surface receptors, they initiate a signaling pathway that activates cyclin proteins, leading to an increase in cyclin levels. Thus, growth factors play a positive role in regulating the cell cycle by stimulating the production of cyclin proteins.