CXCL1 and infection: Of the 39 DEGs identified, there was a marked increase in the expression of mRNA encoding IL-1β, CXCL1, CXCL2, CCL2, CCL4, and CCL7, and a tendency to increase CXCL5 mRNA levels, in S. aureus challenged osteoclasts as early as 4 h post-infection (Fig. 3D).