CASP3 and dermatitis: To determine if the increased dermatitis of SharpincpdmMib2−/− animals was associated with increased cell death, we performed cleaved caspase-3 (CC3) staining on thoracic dorsal skin, a region where the dermatitis phenotype consistently manifests, of age-matched 8- to 9-week-old SharpincpdmMib2−/− and Sharpincpdm mice (Fig. 4A).