As our in vitro experiments indicated that CCND1low/ID1high breast cancer cells exhibit increased invasion and expression of the SNAI2 gene, and our survival analysis indicated that low CCND1 and high ID1 expression can predict RFS in breast cancer patients; we examined all four combinations of CCND1low/high and ID1 low/high gene expression in relation to well-characterised EMT genes in all patients of the same tumour material. This evidence concerns the gene SNAI2 and breast cancer.