While treatment with TNF/SMAC mimetic (SM)/z-VAD-FMK (TSZ) caused time- and RIPK1-dependent necroptosis in human colorectal cancer HT-29 cells, mouse dermal fibroblasts (MDFs) and murine L929 cells, TSZ also triggered ubiquitylation of endogenous MLKL in all these cell types (Fig. 1a–d and Supplementary Fig. 1a–c). Here, TNF is linked to colorectal cancer.