ACKR2 and breast carcinoma: ACKR2 is expressed by a range of cell types, including hematopoietic precursor cells, lymphatic endothelial cells, and specific leukocyte populations such as innate B cells and alveolar macrophages.9 In addition, cancer-associated fibroblasts (CAFs), particularly in breast cancer, express ACKR2.22 While ACKR2 expression in cancer cells is generally low, it can still be detected in certain cancers, such as anaplastic thyroid carcinoma.