ESR1 and breast cancer: Whereas vMCF-7Raf-1 1GX MPS lacked nuclear ERα expression, partial restoration of nuclear ERα expression was observed in vMCF-7Raf-1 1GXCRISPR-NOTCH3 MPS (Fig. 5a and d), corroborating the role of the NOTCH3 signaling pathway in restraining ERα expression in breast cancer cells [38].