CTLA4 and systemic lupus erythematosus: SLE: Systemic Lupus Erythematosus, Tregs: Regulatory T cells, IL-2: Interleukin-2, IL-2R: Interleukin-2 receptor, JAK1: Janus kinase 1, JAK3: Janus kinase 3, STAT5: Signal transducer and activator of transcription 5, PI3K: Phosphoinositide 3-kinase, Akt: Protein kinase B, MAPK: Mitogen-activated protein kinase, Foxp3: Forkhead box P3, CTLA-4: Cytotoxic T-lymphocyte-associated protein 4, IL-10: Interleukin-10, IFN-γ: Interferon-gamma, IL-17: Interleukin-17, TNF-α: Tumor necrosis factor-alpha, NK cells: Natural killer cells