Effect of diacerein and rhein on osteoclast survival. Raw 264.7 cells were incubated for 5 days with RANKL (100 ng/mL) and for an additional 2 days together with RANKL in the presence or absence of interleukin-1-beta (IL-1β) (100 pg/mL) and diacerein or rhein (20 μg/mL). The number of differentiated osteoclasts was determined by the tartrate-resistant acid phosphatase staining assay. Data are expressed as fold changes compared with IL-1β-treated control, which was assigned a value of 1. Statistical analysis was performed versus IL-1β-treated control. RANKL, receptor activator of nuclear factor-κB ligand.