Since CRIPTO-1 physically interacts with all four Notch receptors and Notch4 and Cripto-1 has been shown to be relevant in embryogenesis, maintenance of a human BC stem cell population and tumorigenesis [6, 13, 14], we decided to investigate the role of Cripto-1 in the JygMC(A) mouse model. Here, NOTCH4 is linked to breast cancer.