On the other hand, endogenous level of MnSOD expression in the TIS21−/− MEF along with wt-MEF was much lower in the TIS21−/− MEF than the control (Figure 1D), suggesting that the effect of BTG2 on MnSOD expression was both endogenously and exogenously regulated in mouse fibroblasts and cancer cells, and that there is a possibility of MnSOD gene as a direct target of BTG2. This evidence concerns the gene SOD2 and cancer.