Furthermore, we observed that CD31-positive endothelial cells in PyMT-Fib-cKO tumours expressed comparable levels of ZEB1 relative to PyMT-Fib-WT tumours (Supplementary Fig. 2i; left panels), suggesting that FSP1-Cre does not target endothelial cells in our system. This evidence concerns the gene S100A4 and neoplasm.