Furthermore, as a typical intracellular tumor antigen, the high mobility group box 1 protein (HMGB1) release was also detected by the enzyme-linked immunosorbent assay (ELISA) kit, and the VNP-GD+EI-NP treatment increased HMGB1 expression from 583 pg/ml (control group) to 3083 pg/ml, which was 1.75-fold higher than that of VNP-GD (Fig. 2f), suggesting the enhanced tumor antigen release after the VNP-GD+EI-NP treatment that was attributed to the induced tumor cell pyroptosis. This evidence concerns the gene HMGB1 and neoplasm.