LKB1 knockdown in breast cancer cells causes reduced expression of epithelial markers and acquisition of migratory and invasive properties. (A) Representative immunofluorescent images of NIC-FF and NIC-LKB1 KD cells in 3D collagen cultures stained with E-cadherin (red) and ZO-1 (purple). Nuclei were counterstained with 4',6-diamidino-2-phenylindole (DAPI) (blue) and GFP images are shown to confirm that breast cancer cells retain expression of the control or LKB1-targeting shRNAs. The scale bar in the upper left inset represents 20 μm and applies to all panels. (B) Quantification of the number of cell colonies exhibiting strong junctional protein expression (E-cadherin and ZO-1 staining). The data correspond to an average of three independent experiments. **, P< 0.01. The migratory (C) and invasive (D) rates of NIC-FF and NIC-LKB1 KD cells were assessed using the xCELLigence platform. The data represent an average of three independent experiments performed in duplicate. *, P< 0.05.