ERBB2 and breast cancer: To confirm whether compression induces miR-9 downregulation in breast cancer, CAFs and breast cancer cell lines [MCF7, BT-474, MDA-MB-231, and SK-BR-3: representative cell lines for luminal A, luminal B, Claudin-low (triple negative), and Her2 amplification of human breast cancer, respectively26] were compressed with 0.5, 1, 2, 5, and 10 relative compression units (RCUs, 1 RCU=~0.773 kPa, the compression value of a native tumor microenvironment16) using an agarose-scaffolded alginate bead culture model.