Autophosphorylation at S161 drives RIPK1 kinase activity–dependent apoptosis. (A) Graph depicting quantification of cell death in BMDMs from mice of the indicated genotypes treated with TAK1 inhibitor (TAK1i, 0.25 µM). Graph shows mean ± SEM of three independent experiments. (B) Immunoblots of BMDMs from mice of the indicated genotypes stimulated with TAK1i for 0, 4, and 5 h. Representative of two independent experiments. (C) Kaplan–Meier survival curve of mice with the indicated genotypes. (D) Representative images of sections from back skin of mice with the indicated genotypes stained with H&E or immunostained for CC3 (scale bars = 100 µm; control n = 5, Sharpin^cpdm/cpdmn = 10, Sharpin^cpdm/cpdmRipk1^S161A/S161An = 4, Sharpin^cpdm/cpdmRipk1^S161N/S161Nn = 4). (E) Graph showing the average number of CC3⁺ cells per optical field in mice with the indicated genotypes. Mean ± SEM are shown. Each dot represents one mouse. Statistical significance was determined using Kruskal–Wallis test. (F) Graph depicting measurement of epidermal thickness of mice with the indicated genotypes. Each dot represents one mouse. (G) Graphs depicting relative mRNA expression of the indicated cytokines in RNA from whole-skin tissue of mice of the indicated genotypes measured by qRT-PCR. Each dot represents one mouse. Mean ± SEM are shown. Statistical significance was determined using Kruskal–Wallis test. Control mice include Sharpin^cpdm/WT or Sharpin^WT/WT littermates with WT or mutant Ripk1 alleles. Source data are available for this figure: SourceData F2.