CXCL1 and infection: Production of the neutrophil attractant CXCL1 in infected cells was inhibited by type I IFN signaling as indicated by the increased secretion from type I IFN receptor-deficient macrophages (Supplementary Fig. 2c) and, accordingly, it demonstrated an essentially reciprocal pattern of secretion as compared to IFNβ upon infection with our mutants (Fig. 1f).