BAX and breast cancer: These results (Figure 14 & 15) show that arsenic trioxide is not only inducing apoptosis, cell cycle arrest and regulating the expression of RBBP6 variants but it also upregulates the expression of Bax protein in MCF-7 breast cancer cells, which suggest that RBBP6 variant 1 downregulation may be involved in the intrinsic apoptotic pathway.