As depicted in Figure 3C, the expression of COX-2 was upregulated in the case of PHGFs infected by either ATCC T2 or G231N, E232T, N235D+ adv P. gingivalis strains; infection using each of those bacterial strains resulted in significantly increased expression of COX-2 compared to the wt ATCC 33277 strain (p < 0.001). Here, PTGS2 is linked to infection.