MAPK3 and systemic lupus erythematosus: This pathway shows the potential for the repositioning of existing targets (shaded in blue), such as JAK3, MKK, and ERK1 and ERK2, and the possibility of novel targets (outlined in red), such as CD40, TRAF1 and TRAF6. Indeed, an experimental drug targeting the CD40 receptor is currently in phase II clinical trial for the treatment of lupus nephritis, caused by systemic lupus erythematosus (NCT02770170; https://www.boehringer-ingelheim.com/press-release/phase-ii-trial-now-enrolling-patients-lupus-nephritis).