Another retrospective review further found that patients with non-skull base tumors who experience a recurrence were more likely than patients with skull base tumors to have higher-grade tumors at recurrence [11]. Interestingly, they found a cutoff of 4.5% for MIB-1, a separate marker for cell proliferation, to be a risk factor for recurrence [11,12]. The gene discussed is MIB1; the disease is skull base neoplasm.