Fig. 3A shows extracellular bacteria (panels a, c and e) and total bacteria (panels b, d and f) in untreated or inhibitor-treated cells. Quantification of internalized bacteria is shown in Fig. 3B. Both inhibitors significantly blocked internalization. Similar inhibition of the C. burnetii uptake was observed during infection of a macrophage cell line treated with the MEK kinase inhibitor (Fig. S1A and B). These results suggest that kinases of the Src and ERK families are involved in C. burnetii internalization. Here, SRC is linked to infection.