A nuclear plant worker spilled an extremely radioactive chem…

A nuclear plant worker spilled an extremely radioactive chemical on his skin.  After a few months he started noticing a foul smell and an odd color where he spilled the chemical.  Concerned with his condition, the worker goes to a lab. Upon closer analysis of the patient’s cell growth and production, the doctor notices that the chromosomes of his patient’s cells are mutated and dying because after every round of replication the chromosomes are shortening.  Which one of the following proteins has been inhibited by the radioactive chemical?