Figure 1.

RA is a potent ICD inducer. A) Outline of chemicals screening protocol. Natural compounds were screened by HMGB1‐Gluc reporter assay, the hit compounds were then evaluated by LacZ T cell reporter assay. B) Scatter diagram presentation of the influence of hit compounds on HMGB1 release and LacZ T cell activation. C) Chemical structure of RA. B16‐HMGB1‐Gluc and MC38‐HMGB1‐Gluc cells were treated with indicated doses of RA for 20 h, D) HMGB1‐Gluc luciferase activity and E) extracellular ATP levels were measured. F) B16 and MC38 cells were treated with DMSO or RA (5 µM) for 20 h, and surface expressions of CRT were detected by fluorescence activated cell sorting (FACS). G) MC38 cells were pretreated with DMSO, RA, or freeze‐thawed, followed by subcutaneous inoculation into C57BL6 mice as a vaccine (n = 8). After 7 days, mice were rechallenged with live MC38 cells. The percentages of tumor‐free mice 30 days after rechallenge are shown on the bottom. Data in (D)–(F) are shown as mean ± SD of 3 independent experiments. ^** p < 0.01, ^*** p < 0.001, D,E) one‐way ANOVA test, F) unpaired Student's t‐test, G) log‐rank (Mantel‐Cox) test.