THP-1 cells pretreated with C188-9 (10 μM) or dimethyl sulfoxide (DMSO) (0.1%) 3 h prior to infection with E. chaffeensis exhibited significantly less nuclear STAT3 than DMSO-treated cells at 72 hpi by immunofluorescent microscopy (Fig. 4A and C). Here, STAT3 is linked to infection.