Examination of two markers of cell proliferation, Cyclin D1 and Ki-67, revealed the presence of more advanced (uniformly Cyclin D1-positive) tumors in the MYO1E WT PyMT mice and a higher proportion of cells positive for Ki-67 in the MYO1E WT PyMT tumors and tumor cell cultures (Figure 4). This evidence concerns the gene CCND1 and neoplasm.