Interestingly, in the same study using astrocytes harvested from the same conditional STAT3 knockout mice, the authors also found that transfection of EGFRvIII (epidermal growth factor receptor type III variant) in STAT3+/+ astrocytes resulted in tumor formation in SCID mice, whereas the same treatment did not result in any tumor formation in STAT3−/− astrocytes. The gene discussed is STAT3; the disease is neoplasm.