Although there was no significant difference between the LGR5-overexpressing HeLa cells and GFP control cells with regard to palpable tumor formation (both for 9 days), tumor progression by the LGR5-overexpressing cells was much faster than that by the HeLa-GFP control cells (Fig. 2C, p<0.01). The gene discussed is LGR5; the disease is neoplasm.