fXRT alone (10 Gy/5F, 28.7±2.9% of the tumour cells stained for Ki-67; 20 Gy/5F, 23.3±3.5%) did not have a significant effect on tumour proliferation rates in WT mice compared to those of untreated cohorts (0 Gy, 24.4±2.6%), whereas USMB alone (36.7±3.2%) resulted in a significant increase of proliferation activity. The gene discussed is MKI67; the disease is neoplasm.