SNAI1 and breast neoplasm: To investigate this issue, the potential role of Snail in the invasion of breast tumor cells was assessed at the molecular and cellular level, with the in vitro and in vivo metastasis properties of estrogen receptor (ER)-negative MDA-MB-231 and MDA-MB-435S cell lines transfected with AsSn and DN-RhoA or Act-RhoA vectors.