A recent study showed epithelial-mesenchymal transition of keratinocytes and consecutive skin tumor formation in TROP-2 knockout (ARF−/− C57BL/6) mice (Wang et al. 2011), suggesting that in the context of squamous cell carcinoma, TROP-2 fulfills the function of a tumor suppressor. The gene discussed is TACSTD2; the disease is neoplasm.