Cellular potential for migration and invasion of the 2D and 3D cells were assessed using 24-well Transwell chambers (8 mm; BD Biosciences). For migration assay, a total of 4×104 cells in 200-µl suspension were seeded into the Transwell chamber, while 1×105 cells were seeded in the Matrigel-coated upper chamber for the invasion assay. The lower compartment of the chamber was filled with 500 µl of chemoattractant [conditioned medium prepared from human lung fibroblasts (MRC-5)]. The cells were allowed to migrate or invade for 24 h, after which the non-migratory or non-invasive cells on the top of the filter were carefully removed with cotton swabs. Membrane containing migratory or invasive cells was immersed in 25% methanol for 15 min, developed with 500 µl of 0.5% crystal violet (MilliporeSigma) for 15 min, and acid-extracted with 100 µl of 0.1 N HCl in methanol. The absorbance was measured at 550 nm using a microplate reader.