In vitro studies have demonstrated that i) P. gingivalis strains can induce the expression of the B7-H1 and B7-DC receptors in oral cancer cells, which might facilitate immune evasion by oral cancers [38] and ii) P. gingivalis activates the ERK1/2-Ets1, p38/HSP27, and PAR2/NF-kB pathways to induce proMMP9 expression, after which the proenzyme is activated by gingipains to promote cellular invasion of oral cancer cells [39]. This evidence concerns the gene ETS1 and lip and oral cavity carcinoma.