ERBB2 and breast neoplasm: Utilizing a previously published scRNA-seq,4 including 64,738 cells originating from nineteen primary breast tumors including 7 TNBCs, 8 HR+/HER2-and 4 HER2+, we observed differences in purine and pyrimidine metabolism between TNBC and non-TNBC subjects (Figures 2G, 2H, S4A, and S4B), as well as in a three-group comparison of HR+/HER2-, HER2+ and TNBC subjects (Figures S5A and S5B), illustrating higher activating levels of nucleotide metabolism of TNBC in various cell types including tumor epithelial cells and T cells.