IL1B and rheumatoid arthritis: To further validate the effect of cytokine stimulation on regulation of gene expression, we isolated FLS from two of the same RA synovial tissue samples subjected to scATAC/RNA-seq (RA4 and RA5 from Supplementary Table 1), stimulated them at passage 3 with TNF, IFN-γ and IL-1β or TNF and IFN-γ and performed scATAC/RNA-seq.