TNFSF11 and neoplasm: In this study, we aimed to clarify the unknown factors responsible for osteoclastogenesis induced by OSCC cells using a subclone of OSCC cells which did not have osteoclastogenic properties, selected IL-1 as a stimulator of both tumor-induced and RANKL-induced osteoclastogenesis, and examined the biological significance of IL-1 in bone resorption induced by OSCC.