E2F1 and rheumatoid arthritis: These cluster-specific TFs, such as the CL1-specific RARα, ETV7, BCL6, BACH1, NFE2L1, THRA, and NR0B1, and the CL2-specific TCF7, E2F7, E2F1, FOSL1, and FOXC2, collectively regulate the differential functions of the two groups of RA cell lines.