SETDB2 and breast cancer: We further restored SETDB2 wildtype and SETDB2 2GA mutation in SETDB2 knockdown SUM159PT breast cancer cells (Fig. 2B and Fig. S6), and found that both SETDB2 wildtype and SETDB2 2GA mutation significantly decreased the percentage of abnormal nuclei (Fig. S5A and Fig. 2C), abnormal phenotype of spindle and chromosome segregation in metaphase and anaphase (Fig. S5B and Fig. 2D), and G2/M arrested cell (Fig. S5C and Fig. 2E).