PYR-41 is an irreversible, cell permeable inhibitor of ubiquitin-activating enzyme E1 UBA1 (ubiquitin-activating enzyme E1), which has been reported to inhibit the expression of IgE, IFN-γ and also reduced ear thickening and skin damage in mouse models of atopic dermatitis, associated with the inhibition of the NF-κB signaling pathway (74). Here, UBA1 is linked to atopic eczema.