To directly assess the importance of stromal fibroblast-derived p53 as a ZEB1 target during mammary tumour growth and progression in vivo, we generated female cohorts with the genotypes of MMTV-PyMT;ZEB1fl/fl;p53wt/wt (PyMT-Fib-WT mice), MMTV-PyMT;FSP1-Cre;ZEB1fl/fl;p53wt/wt (PyMT-Fib-ZEB1-cKO) and MMTV-PyMT;FSP1-Cre;ZEB1fl/fl;p53fl/fl (PyMT-Fib-ZEB1/p53-dcKO). The gene discussed is S100A4; the disease is breast cancer.