As with the mRNA levels, the protein levels of δEF1 and E-cadherin were reciprocally regulated: most cell lines with low δEF1 levels and high E-cadherin levels were categorized into the luminal and Basal A subtypes of breast cancer, whereas those with high δEF1 levels and low E-cadherin levels were categorized into the Basal B subtype (Fig.1A). Here, CDH1 is linked to breast cancer.