SNAI1 and neoplasm: Though we failed to detect a further increase in the number of VIM-positive cells by E2-treatment in BRCA1 mutant PDX tumors (Fig. 3b), the number of tumor cells that are positive for fibronectin, another key marker of mesenchymal cells, and for SNAIL and SLUG was drastically enhanced by E2 relative to the placebo (Fig. 3b).