The main objectives of the present work were to newly investigate: (i) whether ZNF217-ΔE4 is expressed in primary breast cancers; (ii) if so, whether ZNF217-ΔE4 mRNA levels possess any clinical relevance; and (iii) whether increased expression levels of ZNF217-ΔE4 functionally affect the phenotype of breast cancer cells. This evidence concerns the gene ZNF217 and breast cancer.