cell cycle and cell divivsion
This occurs in G2 phase. G2 phase is the gap after S phase and before cell division. What happens during the G2 phase of interphase is continuous growth and checking of the new DNA to ensure there are no errors as the DNA is formed, if there are errors, they are repaired and the process of division is started.
When microtubules are needed to form the mitotic spindle, there will be a sharp increase in production of a protein called Tubulin to ensure that micro tubules are made.