It is speculated that DLL4+ Mo-LCs play important roles in psoriatic lesions given the increased expression of DLL4 in psoriasis lesional skin (28, 29), the relationship between Mo-LC and psoriasis (5–7, 13), the high level of expression of TLR2 on blood monocytes in patients with psoriasis (33), the fact that the TLR2 ligand PGN most potently induces DLL4 expression (Figure 3), and that DLL4+ Mo-LCs most potently activate T cells (Figure 6). The gene discussed is TLR2; the disease is psoriasis.