Cell line characteristics.

Characteristics of cell lines investigated: receptor status and aggregate morphology.*Tumor receptor status: + = positive and— = negative for ER = estrogen receptor, PR = progesterone receptor, and HER2 = human epidermal growth factor receptor 2. In cases where discrepancy between reports is present across publications, both reported receptor statuses are shown [18, 33].+Aggregate morphology in a “3D on top” lrECM assay (cells on an lrECM gel and covered with an additional thin layer of lrECM) as reported by Kenny et al. [18].#Aggregate morphology on 2D glass and in 3D 1.0 mg/mL collagen I matrix from this study.Cell line characteristics.