To directly investigate the role of mutant p53 in stroma on breast tumor development, we generated a cohort of female mice with the following genotypes: MMTV-neu; Fsp-Cre; Trp53wm-R172H/+ (NP) and MMTV-neu; Fsp-Cre or Trp53wm-R172H/+ (N). The gene discussed is ERBB2; the disease is breast neoplasm.