MDA-MB-231 cells were seeded onto FBS-coated glass coverslips at a density of 2.0 × 105 cells/well and cultured for 48 h at 37 °C. Cells were treated with 100 ng/ml of purified recombinant cmvIL-10 for 96 h, then fixed with 2% paraformaldehyde in DPBS for 20 min, washed, permeabilized with 0.2% Triton-X-100 in PBS for 15 min. The cells were washed and blocked with 10% FBS for 1 h at 37 °C, then incubated with anti-MTSS-1 antibody at a 1:100 dilution for 1 h at 37 °C followed by the addition of goat anti-mouse TRITC secondary antibody at a 1:150 dilution for 30 min (Life Technologies) and Alexa Fluor 488 phalloidin (Molecular Probes, Eugene, OR). Coverslips were washed and excess fluid was removed before inverting the coverslip onto a glass slide containing 20 μl of DAPI-containing Prolong Gold mounting medium (Life Technologies, Grand Island, NY). Images were taken on a Zeiss AX10 Imager.A1 microscope (Carl Zeiss Inc., Oberkochen, Germany) using AxioVision 4.7.2 imaging software.