These results indicate that osteoclastogenesis in RANKL-primed RAW-D cells induced by infection with P. gingivalis is dependent on the expression of NFATc1 and p38 MAPK but is not dependent on expression of NF-κB, whereas osteoclastogenesis induced in these cells by RANKL is dependent on NF-κB as well as on NFATc1 and p38 MAPK. The gene discussed is NFATC1; the disease is infection.