NOTCH3 and breast cancer: In order to evaluate the oncogenic potential of NOTCH1 and NOTCH3 on breast cancer growth in vivo, we used the CRISPR-/Cas9-based genomic editing to prepare MCF-7 breast cancer cell-based KO cell lines lacking endogenous expression of either NOTCH1 or NOTCH3 genes and the corresponding proteins (Fig. S1, A–C).