APOBEC3B and breast cancer: We extended our analysis by stratifying the breast cancers using PAM50 classification and found immune scores in luminal A and basal-like breast cancers from METABRIC to be significantly different across APOBEC3B copy number (P = 0.02 and P = 0.01, respectively) but not in luminal B and HER2-enriched breast cancers nor in any of the subtypes of breast cancers from TCGA (Additional file 1: Figures S2 and S3).