Stable knockdown of CBFβ inhibits invasion of MDA-MB-231 cells. (A) Western blot showing knockdown of CBFβ in two independent clones. Total lysates from wild type (WT) MDA-MB-231 cells and two stable transfectants harbouring a plasmid containing shRNAs against CBFβ (shCBFβ) or a plasmid with a non-specific shRNA (shNS) were subject to western blotting analysis to determine CBFβ expression. Tubulin was used as a loading control. (B) Western blot showing expression of Runx2 in CBFβ-knockdown cells. The upper panel shows nuclear extracts from stable knockdown cells (shCBFβ) and the stable non-specific cells (shNS) after immunodetection with an anti-Runx2 antibody. The lower panel is a Lamin B1 loading control. (C) CBFβ is essential for invasion. Both CBFβ-knockdown clones and the non-specific stable clone were plated on Matrigel to determine their invasive capacity. Wild type (WT) MDA-MB-231 cells were used as positive control for invasion. Cells that migrated were stained and counted in random fields. Data are presented as mean ± standard deviation (S.D.) (n = 3). * indicates p < 0.05 compared with shNS by analysis of variance.