Then, these mice were crossed with MMTV‐PyMT transgenic mice, a classic spontaneous mammary tumor model, to obtain Znf8fl/fl; MMTV‐ PyMT (WT), Znf8 fl/fl; MMTV‐Cre; MMTV‐PyMT (KO) and heterozygous knockout mice (Znf8fl/+; MMTV‐Cre; MMTV‐PyMT (Het)) (Figure 3E). This evidence concerns the gene ZNF8 and breast cancer.