TLR4 and mastitis: MiR-125b [13] and miR-146a [14] aggravate and alleviate mastitis in dairy cows by targeting the NF-κB inhibitor-interacting Ras-like 2 (NKIRAS2) and Toll-like receptor 4 (TLR4)/tumor necrosis factor receptor-associated factor 6 (TRAF6)/NF-κB pathways, respectively.