Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

a. disruption of mitotic spindle formation.

b. suppression of cyclin production.

c. myosin denaturation and inhibition of cleavage furrow formation.

d. inhibition of DNA synthesis

a. disruption of mitotic spindle formation.

Explanation:

Vinblastine is a chemotherapeutic drug which is used to restrict cancer cell proliferation. During metaphase, it binds to microtubular proteins which play a very important role in mitotic spindle formation. If spindles will not form then during anaphase, the sister chromatids will not separate and mitosis will not take place. This is how hyper-proliferative cancerous cells are controlled from dividing and cancer is treated using this drug.