The gene expression levels of C/EBPβ, RUNX2, Cathepsin K, and NFATc1, which associated with osteoclast-prone phenotype and function, were compared in the fresh isolated CD14+ monocytes from HC, RA patients with lower expression level of CPT1A, and RA patients with higher CPT1A expression. Here, CTSK is linked to rheumatoid arthritis.