IRF5 and infection: Quantitative real time PCR (qRT-PCR) of RNA in SCC-25 cells after 24 h of infection with P. gingivalis total membrane (Fig. 1) showed statistically significant up-regulation of the following genes: IκBκB (4.7 ×), MAP2K4 (4.6 ×), MAPK14 (4.2 ×) and IRF5 (9.8 ×) (p < 0.01) (n = 9).