RAC1 and breast cancer: In terms of oncogenic copy number variations (CNVs), MMR-altered breast cancers displayed significantly increased frequencies of MYC amplification (38.5% vs. 20.3%), RAD21 amplification (35.9% vs. 16.9%), RECQL4 amplification (28.2% vs. 15.2%), PMS2 deletion (18.0% vs. 0.0%), FAT1 deletion (12.8% vs. 1.3%), and RAC1 deletion (12.8% vs. 0.04%) (Figure 4C,D).