ATR and breast cancer: The top three signaling pathways being altered in our breast cancer cohort were genome integrity (TP53, ATR, ATM, BRCA1/2), Phosphoinositide 3‐kinase PI3K signaling (PIK3CA, PTEN, AKT1) and Switch/Sucrose non‐fermentable SWI/SNF chromatin remodeling complex (ARID1A, ARID2, SMARCA4) with the mutation frequency of 64.6%, 55.9% and 26.0%, respectively (Fig. 3A).