The expression level of intrinsic apoptosis (BAX, caspase 3 and caspase 9) and stress (p21, HSP 70 and HSP90)-related transcripts was quantified by analysis of Ct value using real-time RT-PCR assay in A-549, MDA-MB-231 and U87-MG cancer cells treated with 1 μM SMA, as shown in Figure 6. This evidence concerns the gene CASP3 and cancer.