IL1B and rheumatoid arthritis: Notably, the selected concentrations of 0, 50, 100, and 200 μM of silibinin (cells treated for 48 h) dose-dependently induced the apoptosis of RA-FLS cells (apoptosis rates were approximately increased by 5% from 50 to 100 μΜ and from 100 to 200 μΜ), while in a similar way the same selected doses inhibited TNF-α-induced IL-6 and IL-1β production.