To assess the functional significance of the relative overexpression of APOEC3G in CD44+ mesenchymal glioma cells compared with CD44− glioma cells, we depleted APOBEC3G expression using lentivirus expressing shRNA directed against APOBEC3G in A172, U343, and GSC20 cells (Figure 2A). The gene discussed is APOBEC3G; the disease is glioma.