RNPEP and infection: In contrast to HL-60 infection, the ApB mRNA is transiently upregulated after infection of ISE6 cells (Figure 1(c) and (d)), which mirrors the ClpB expression pattern during the infection of macrophages with an intracellular pathogen E. chaffeensis.6 Altogether, the results in Figure 1 suggest that A. phagocytophilum ClpB and DnaK play a role in the pathogen’s adjustment to an intracellular environment of the host and the in-host proliferation.