IL17A and skin disorder: Crossing ΔKerOTULIN mice onto a TNFR1-deficient background completely prevented dermatitis (Fig. 3a), even at old age (Supplementary Fig. 3a), and ΔKerOTULIN-TNFR1−/− mice showed significantly reduced IL6, TNF, and IL17 levels in their serum (Fig. 3b).