The dermatitis in Sharpincpdm-Dem, Il4ra−/− mice was much more severe than in the Sharpincpdm-Dem mice (Fig. 3 B, D) and was associated with significantly increased epidermal thickening(p≤0.001) (Fig. 3 U) exceeding that in the Sharpincpdm-Dem, Rag1−/− mutants, although in this case it was also accompanied by significantly greater numbers (p≤0.001) (Fig. 3 V) of cleaved CASP3 and 9 positive, apoptotic cells (Fig. 3 L, P) compared to Sharpincpdm-Dem (Fig. 3 J, N) or WT controls (Fig. 3 I, M, K, O). Here, RAG1 is linked to dermatitis.