ERBB2 and breast carcinoma: To study the roles of bASCs in this aspect, we formed hybrid spheroids consisting of bASCs and low-malignant MCF7(ER+, PR+, HER2+), BT474(ER+, PR+, HER2+) or high-malignant MDA-MB-231(ER-, PR-, HER2-) breast cancer cell lines [27] as displayed in Fig. S7A. These hybrid spheroids were formed with different percentages (85, 70 or 50%, respectively) of breast cancer cells together with 15, 3% or 50% of bASCs.