CD4 and dermatitis: As skin inflammation progressed to overt disease (~5 mo), the frequency of Vβ4+ CD4+ T cells increased ~3 fold and in 5–6 mo Sox13-/- mice the total number of skin CD4+ T cells was more than 10-fold greater in Sox13-/- mice than WT mice, depending on the skin site, with up to 50% of these cells expressing Vβ4 TCR (Figure 6A–C).