While A375/bcl-xl-siRNA tumors tended to progress slowly (167±38 mm3, approximately 13.8% of the tumor volume calculated for control A375 tumors 3 weeks after inoculation), A375/bcl-2-siRNA tumors tended to regress (86 ± 25 mm3 1 week after inoculation, and < 20 mm3 3 weeks after inoculation) (Figure 2E) (expression levels of the relevant apoptosis-related proteins in the tumors assessed in Figure 2E are presented in Additional file 1 Table S1). This evidence concerns the gene BCL2 and neoplasm.