Tumours collected from mice at diestrus exhibited a significant increase in the expression of genes Mki67 (p = 0.05), Ccnb1 (p = 0.02), Erbb2 (p = 0.03), Grb7 (p = 0.02), and Bag1 (p = 0.05), compared to tumours collected at estrus. The gene discussed is GRB7; the disease is neoplasm.