Figure 2. NF-B-mediated up-regulation of different Bcl-2 genes. One possible way to explain the dichotomous responses of normal cells and tumor cells to anti-neoplastic activation of NF-B might be that different Bcl-2 genes are up-regulated. In normal cells, those genes (Bax, Bak, Bik, Bicl) are associated with apoptosis, while those in tumor cells (Bcl-X2, Mcl-1, Bcl-w, A-1, Bfl-1) might be cytoprotective.