library_construction_protocol: Ter119+CD71+ splenic cells from anemic mice (A-EPCs), splenic CD45+Ter119+CD71+CD11b-C-kit- cells (T-EPCs), and intratumoral CD45+Ter119+CD71+CD11b+Gr1+ (EDMCs) and CD11b+Gr-1+ (MDSCs) from mice bearing late-stage tumors were sorted by FACS. For patient samples, CD235a+ bone marrow cells from bone-metastasis-free patients with advanced tumors, or CD45+CD235a+CD71+ cells from MPE were sorted by FACS, as indicated. Single cells were suspendend in calcium- and magnesium-free PBS containing 0.04% weight/volume BSA,then the cell suspension was loaded into Chromium microfluidic chips with 3' chemistry and barcoded with a 10× Chromium Controller RNA Libraries were constructed using a Chromium Single Cell 3' v1 Chemistry kit (10x Genomics) according to the manufacturer's protocol