BIRC5 and breast carcinoma: In this present study, CRISPR/Cas9 technology and Tet-off regulatory system were used to successfully establish a quantitatively regulated system to control the expression of Survivin in the breast cancer cell MCF-7 (when the concentration of doxycycline was ≤6,750 nmol/ml, it will not affect the viability of MCF-7 cells within 72 h).