The distinct effect of CA7 compared to other cytosolic carbonic anhydrase isoforms in HER2-enriched breast cancer is consistent with the expression of CA7 exclusively in cancer-associated fibroblasts and myeloid cells, whereas expression of the other cytosolic carbonic anhydrase isoforms (CA1, CA2, CA3, and CA13) is most prominent in cancer epithelial and endothelial cells (Fig. 2B). Here, ERBB2 is linked to breast cancer.