MiR-let-7a downregulation augments the inflammatory response by increasing ACPA-mediated ERK1/2 and JNK phosphorylation and inducing IL-1β release via Ras proteins.147 In addition, Zhu et al. reported that miR-let-7a can inhibit ACPA-induced macrophage activation by directly targeting HMGA2.148 In contrast, high expression of miR-let-7b provokes arthritic joint inflammation. Here, PRTN3 is linked to Arthritis.