IL1B and rheumatoid arthritis: When IL-1β-activated RA-FLS were subjected to a combination of MTX and the NF-κB activation inhibitor BAY 11–7085, the MTX-mediated increase in CSF2 expression was abrogated in some, but not all, of the tested RA-FLS (fold change to untreated activated control 1.8 ± 0.8 with MTX + BAY 11–7085 versus 2.6 ± 0.3 with MTX alone, p = 0.52) (Fig. 4A).