CD44 and breast cancer: Having validated that HLA-ABC can identify both PanCK+ and CD44+ breast cancer cells in mouse bone marrow, we depleted doublets (SSC-H v SSC-A) and dead cells (DAPI+), normal blood cell lineages (leukocytes: CD45+, lymphocytes, mesenchymal, endothelial progenitors: CD34+, macrophages, fibroblasts CD90+/CD105+, mesenchymal, hematopoietic stem cells, NK cells: CD73+) by FACS, and implanted the residual CTC-enriched/lineage-negative cells into NOD scid-gamma (NSG) mice by intracardiac injection [20,28,29].