(A-D) Intracellular H2S in immortalized MEFs treated with teniposide (Ten) for 6 h (A) or up to 24 h (B), or 24 h after ultraviolet-C (UVC) (C) or ionizing radiation (IR) (D) exposure (n=3). (E, F) Intracellular H2S levels in primary MEFs (E; n=3) or primary MDFs (F; n= 3) treated with Ten for 6 h. (G) Intracellular H2S levels in bone marrow cells from mice treated by intraperitoneal injection of etoposide (Eto) (n=3 or 4/group). (H) Intracellular H2S levels in circulating leukocytes from Csa−/−/Xpa−/− (Cx) mice (n=3). (I, J) Intracellular sulfane sulfur (I) and medium H2S (J) levels in primary MEFs treated with Ten for 6h (n=3). (K) Intracellular H2S levels in immortalized WT and PARP-1 knockout (KO) MEFs treated with Ten for 6 h (n=3). (L) Intracellular H2S in immortalized MEFs treated with 5 μM pan-caspase inhibitor Z-VAD-FMK (Z-VAD) and Ten for 24 h (n=3). Probe SF7-AM was used for intracellular and medium H2S measurements. Probe SSP4 was used for intracellular sulfane sulfur assay. Error bars indicate SD. ns, not significant; *P < 0.05; **P < 0.01; **** P < 0.0001. One-way ANOVA (A-E, I, J); Two-way ANOVA (K, L); Student’s t-test (F-H).