These treatments induced similar kinetics of apoptosis in the human melanoma A375 cell line (Supplementary Fig. 1A) but only MTX and Hyp-PDT elicited classical in vitro markers of immunogenic apoptosis, including surface-exposed CRT (Supplementary Fig. 1B), ATP release—particularly after Hyp-PDT (Supplementary Fig. 1C)—and cytoplasmic redistribution of nuclear HMGB1 prior to its passive release (Supplementary Fig. 1D, E), confirming previous studies [3, 13–15]. The gene discussed is HMGB1; the disease is melanoma.