RT Journal Article SR Electronic A1 Lederman, Lynne T1 Development, Safety, and Efficacy of Janus Kinase Inhibitors in Rheumatoid Arthritis JF MD Conference Express YR 2013 FD SAGE Publications VO 13 IS 18 SP 31 OP 32 DO 10.1177/155989771318015 UL http://mdc.sagepub.com/content/13/18/31.abstract AB The four Janus kinases (JAKs), JAK1, JAK2, JAK3, and Tyk2, are essential components of the signaling pathway of certain cytokines [O'Shea JJ et al. N Engl J Med 2013]. This article reviews the role of JAKs in inflammation and JAK inhibitor efficacy and toxicity, the clinical data for tofacitinib, as well as discusses kinase inhibition in development, baricitinib, which strongly inhibits JAK1 and JAK2.