TP53 and neoplasm: The MMTV-Hras/p53+/+ tumor cells were relatively uniform in size and shape, while both the MMTV-Hras/p53-/- and MMTV-Hras/p53R172H/R172H tumor cells displayed more variability in cell and nuclear size and shape and less evenly distributed chromatin in the nucleus (Fig. 4).