These results suggest that MST2 plays a tumor-suppressive role in a subset of low grade differentiated OSCC and well-defined invasive fronts (YK-1–3), but it may be a tumor-promoting factor in OSCC showing poor differentiation and in a subset of OSCC with an aggressive mode of invasion (YK-4C and 4D). The gene discussed is STK3; the disease is neoplasm.