STAT3 and cancer: As EMT is a key process for cancer cell migration and invasion, defined by loss of epithelial cell polarity and reorganization of the cytoskeleton, and STAT3 is activated in tumors as the form of pY-STAT3 (17), we next examined the expression of epithelial and mesenchymal markers of EMT and pY-STAT3 protein expression in STAT3-inhibited Cal-27 cells.