Impact of Receptor Activator of Nuclear factor κB (RANK) over-expression in osteosarcoma cells on tumor growth and the number of lung metastases. No significant difference was observed concerning tumor growth regardless of the cell-line considered (K-HOS (A), MOS-J PG1 (C,E)) or the immune status of the host mouse strain (Nude (A,C) or C57BL/6 (E)). However, regarding the number of lung metastases, a significant increase was observed regardless of the RANK over-expressing cell-line considered, in immune-deficient Nude mice (B,D) but not in immune-competent C57BL/6 mice (F). Moreover, injections of a Receptor Activator of Nuclear factor κB Ligand (RANKL)-blocking antibody (IK22.5) in Nude mice made it possible to reduce the number of lung metastases obtained with RANK expressing PG1 (D). n: number of mice in each group. Growth curves (A,C,E) are shown as the mean ± SEM. All data analysis was performed with the Kruskal Wallis test. ns: not significant; **: p < 0.01; ****: p < 0.0001.