We also found for the first time that neutralizing IL12p40 secretion could inhibit proliferation, enhance apoptosis, induce a G0/G1 arrest, restrain T helper 1 type immune responses, and promote chemokine C-C motif ligand 20-mediated migration of human CD4+ T cells, which might be the mechanisms why anti-IL12p40 treatment presented efficacy in CD. This evidence concerns the gene CD4 and Cowden disease.