a, Quantification of the chromosome number in cells after treatment with with 0.1 µM of Reversine (Riv) for 24hrs before and after 4 days in 3-D cultures (~20 chromosome spreads were quantified in each condition). The concentration of Reversine used does not induce cytokinesis failure and therefore would not induce centrosome amplification by inducing tetraploidy. b, Fraction of invasive acini after MCF10A cells are treated with Riversine. Increased aneuploidy from Riversine treatment does not induce invasion. Error bars represent mean ± SE from 3 independent experiments. c, Images of 3-D cultures after treatment with Riversine showing normal appearing acini. Scale bar: 50µm. d, SNP analysis of MCF10A cells (without centrosome amplification) compared with Human Reference Genomic DNA 103 from Affymetrix. Previously reported genomic alterations in MCF10A cells can be detected in our analysis, namely: +5q, +6p and +8q.