MRC1 and neoplasm: Further, when M0 cells were evaluated for tumor cell- or fibroblast-derived material (indicated by PKH signal), tumor cell-derived PKH26 was found to be significantly increased in M0 cells expressing CD163 and CD206 when compared to fibroblast-derived PKH67, suggesting tumor cells skew M0 cells to polarize towards M2-like macrophages (Figure 5E).