CASP3 and neoplasm: To determine the effect of VPA/HPTA-activated macrophages on tumors, we found that the proportion of apoptotic cells (Cleaved caspase-3+) was increased after VPA/HPTA treatment and RT-alone treatment, this was further increased after the combined treatment (2.03 ± 0.43/1.90 ± 0.41, P <0.01, Figure 4A), suggesting that the combination treatment promoted the apoptosis of tumor cells.