Fig. 6

Cleaved caspase-3 expression after death-switch induction. a Percentage (%) caspase-3-positive cells in B16ova and B16ovaRevC3 tumour sections at 6 and 24 h after doxycycline administration. Caspase-3 expression was not detected in control B16ova or B16ovaRevC3 tumours; however, significantly increased caspase-3 expression was observed in B16ovaRevC3 tumours after death-switch induction, which was also significantly higher compared with B16ova tumours from mice treated with doxycycline (p < 0.05 and p < 0.05, respectively, multiple t tests). b Representative tumour sections stained for cleaved caspase-3 expression. c Representative whole tumour sections showing a heterogeneous mix of necrosis, immune reaction, patches of tumour cells positive for caspase-3 within a dense stroma, adipose formation and vesicularization following death-switch induction. * indicates significant difference between doxycycline-treated B16ovaRevC3 and control B16ovaRevC3, and doxycycline-treated B16ova