HRAS and lymphoma: Significant fractions of the p53-/- and p53R172H/R172H mice developed symptoms indicating the presence of lymphomas and/or sarcomas prior to the development of salivary tumors, consistent with previous reports of the prevalence of these tumor types in p53-/- and p53R172H/R172H mice lacking the MMTV-Hras transgene [2–5,43,44], which necessitated sacrifice of the mice.