Coculture of GFP-231 with MSCs resulted in 89% GFP+/DsRed+ hybrid cells (Figure 2C), and coculture of GFP-CCN6–KO cells with DsRed-MSC cells for 7 days led to 95% hybrid cells (Supplemental Figure 2D), representing well-suited experimental cell models to investigate the role of hybrid cells in breast cancer progression. This evidence concerns the gene CCN6 and breast cancer.