ESR1 and neoplasm: Furthermore, the increase in Vim expression and conversion of cells from Vim-negative to positive by E2 in p18−/−;Brca1MGKO tumor cells was not blocked by 4OHT (Fig. 3g, h), whereas, 4OHT effectively blocked E2-enhanced cell proliferation and RB phosphorylation in ER-positive MCF7 cells, as expected (Additional file 7: Figure S7).