library_construction_protocol: We labeled HCC70, MCF7, MDAMB231, MDAMB231-S, and MDAMB231-NS cells separately with the Sample-Tags from the BD Human Immune Single-Cell Multiplexing Kit (BD Biosciences) as described in the manufacturer's protocol. We prepared a library from ~5000 cells (approximately 1000 cells from each group) using the BD Rhapsody System following the BD “mRNA Whole Transcriptome Analysis (WTA) and Sample Tag Library Preparation Protocol”.