GLK overexpression in Lck-GLK Tg T cells or T cells of patients with SLE selectively induces IL-17A production; however, GLK deficiency (mimicked by high-dose verteporfin treatment) blocks the production of both NF-κB–induced Th1 or Th2 cytokines and AhR–ROR-γt–induced IL-17A. The gene discussed is GCK; the disease is systemic lupus erythematosus.