As STAT3 is known to play an important role in promoting self-renewal of cancer stem cell enrichment and to give rise to tumorspheres, we performed a tumorsphere formation assay in vitro with HD-shSTAT3 and ONS-shSTAT3 cells grown in serum-free medium in ultra-low adherent tissue culture plates [40,41]. The gene discussed is STAT3; the disease is cancer.