RAW264.7 macrophage cells were cultured in RPMI 1640 containing 10% FBS and 1% antibiotic-antimycotic mixture at 37 °C and 5% CO2. Human fetal osteoblastic cells (hFOB1.19; American Type Culture Collection, Manassas, VA) were cultured in DMEM/F-12 containing 10% FBS and 1% antibiotic-antimycotic mixture. Immortalized human oral keratinocytes (IHOK), immortalized human gingival fibroblasts (IGF), and YD38 human gingival epithelial cells were obtained from the Yonsei University College of Dentistry, Republic of Korea, and all were cultured in DMEM/F12 (3:1 ratio) as previous detailed . Mouse bone marrow-derived macrophages (BMMs) were isolated from the tibias of 4-week-old ICR male mice using Histopaque density gradient centrifugation. BMMs were cultured in α-MEM containing 10% FBS, M-CSF (30 ng/ml), and a 1% antibiotic-antimycotic mixture.