What external stimulation is required by mammalian cells to progress through the cell cycle prior to reaching the restriction point?
A)presence of steroid hormones in their culture medium
B)presence of Na+ ions in their culture medium
C)presence of growth factors in their culture medium
D)no external stimulation is required
E)presence of vitamins in their culture medium

Question

Quizplus · Accepted Answer

Mammalian cells require external growth factors to progress through the cell cycle prior to reaching the restriction point. The presence of growth factors can promote the activation of signaling pathways that drive the cell cycle forward. Without these external signals, cells may become arrested in the G1 phase and not progress further.

What External Stimulation Is Required by Mammalian Cells to Progress