We received KRN mice from Dr. Mathis and followed their protocol to collect K/BxN serum from the F1 progeny; we then induced arthritis in KLF2 hemizygous mice as well as in monocyte-specific conditional KLF2 knockout mice, which were developed and characterized in the Jain laboratory (CWRU, Cleveland). Here, KLF2 is linked to arthritic joint disease.