 on AGS cells were assessed with Transwell and Matrigel assays.  The number of cells that had migrated through the culture insert pores (up) or had invaded through the Matrigel insert pores (down) was photographed using a 00X microscope objective.  (TIF)  ######   Click here for additional data file.  [^0]: **Competing Interests:**The authors have declared that no competing interests exist.  [^0]: Conceived and designed the experiments: Z