HRAS and neoplasm: In conclusion, this study has led to the generation of MMTV-Hras/p53R172H/R172H mice and a comparison between these mice and the previously characterized MMTV-Hras/p53+/+ and MMTV-Hras/p53-/- mice, with regard to salivary tumorigenesis, tumor properties, tumor responses to a chemotherapeutic agent, and tumor gene expression profiles.