SOX9 and breast carcinoma: Moreover, IC50 of p53 knockout CAL-51 cells (Redman-Rivera et al., 2021) (0.88 μM) was comparable to that of wild-type CAL-51 cells (0.74 μM) (Figure 2—figure supplement 3B and D), further supporting the notion that CMPD1 induces a robust prometaphase arrest in breast cancer cells via a p53-independent mechanism.