Subsequently, MDA-MB-231 xenograft mice that were treated with the LSD1 inhibitor phenelzine, had reduced tumor growth and the tumor cells isolated showed a downregulation of LSD1 expression and other CSC markers such as cell surface vimentin (CSV), aldehyde dehydrogenase 1 family, member A1 (ALDH1A1) and ATP-binding cassette sub-family B member 5 (ABCB5). This evidence concerns the gene ALDH1A1 and neoplasm.