Because i) Syk is a downstream of Fc gamma receptors and TLR-4 through immunoreceptor tyrosine-based activation motif (ITAM) and non-ITAM dependent pathways, respectively (37), ii) Syk is a possible shared downstream signaling from TLR-4, Fc gamma receptors and PMA (Figure 10), which activated the Syk through ROS from NOX2-dependent PMA stimulation (102), and iii) Syk also enhances ROS production (104, 105) that could accelerate both apoptosis and NETosis (102), and this inhibitor is an interesting drug for use in lupus. Here, TLR4 is linked to systemic lupus erythematosus.