PTPRC and breast cancer: Flow cytometric analysis of dissociated mammary tumors at 16 to 18 weeks of age reveals that transplantation of NG2 null bone marrow, regardless of the recipient genotype, results in reduced numbers of tumor-associated macrophages (TAMs) characterized by the marker phenotype F4/80-positive, CD11b-positive, CD45-positive, Gr1-negative (Figure 6I-K).