NFKB1 and mastitis: When the bacteria causing mastitis pass the teat canal barrier, bacterial byproducts (such as lipopolysaccharides (LPSs) or the outer-membrane vesicles (OMVs) of Gram-negative bacteria) act as pathogen-associated molecular patterns (PAMPs) to activate PRRs (including TLRs, NLRs, and RLRs) in macrophages, dendritic cells, and mammary epithelial cells, thereby further activating the NF-κB and MAPK signaling pathways [42].