a, Confocal microscopy of BMDMs stimulated with LPS and treated with arsenite (Ar) (1 h), nigericin (N) (45 min), or arsenite (30 min) followed by nigericin (45 min), stained for G3BP1 and ASC. Scale bars, 10 μm. Representative images (n > 3). b, Immunoblot analysis of pro-CASP1 (p45) and cleaved CASP1 (p20), and GSDMD (p50) and cleaved GSDmD (p30). Representative images (n = 3). c, Enzyme-linked immunosorbent assay measurement of IL-1β and IL-18. ****P < 0.0001 (unpaired two-sided t-test; n > 10). d, Measurement of pyroptosis by SYTOX Green staining. ****P ≤ 0.0001 for LPS + N versus LPS + Ar + N (two-way analysis of variance (ANOVA); n = 4). e, Measurement of pyroptosis by SYTOX Green staining in BMDMs stimulated with LPS and treated with arsenite and nigericin, with or without removal of nigericin after 15 min of treatment (N(R)). ****P ≤ 0.0001 for LPS + N(R) versus LPS + Ar + N(R) (two-way ANOVA; n = 4) Data are mean ± s.e.m. (c-e). f, Immunoblot analysis of CASP1 in BMDMs stimulated with LPS and treated with nigericin, arsenite and anisomycin (An) as indicated. Representative images (n > 6). g, Measurement of IL-18 and IL-1β from LPS-stimulated BMDMs treated as indicated. P values (from left to right): ****P < 0.0001, *P = 0.0109, ****P < 0.0001, ***P= 0.0003 (unpaired two-sided t-test; n> 6). h-k, Immunoblot analysis of CASP1 cleavage (representative blots, n > 2) and measurement of IL-1β in LPS-stimulated BMDMs treated with arsenite and imiquimod (Im) (h; n= 4), silica (Si) (i; n= 2), Pam3CSK4 (Pam3) with or without nigericin (j, n = 4), or curdlan (Cn) with or without nigericin (k, n= 2). P values (from left to right): ****P < 0.0001, ****P = 0.0001 (unpaired two-sided t-test). Data are mean ± s.e.m (g-k).