RIPK1 and colorectal cancer: 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).