RAC1 and breast cancer: Moreover, our study suggests that KRT19 directly interacts only with β-catenin and is translocated to LEF1/TCF7 promoter to promote colon cancer progression, whereas KRT19 directly interacts with the β-catenin/RAC1 complex and is predominantly translocated to the NUMB promoter in breast cancer and is suppressed through attenuation of Notch signaling (see Figure 6a,b).