NFKB1 and bacterial infectious disease: Upon bacterial infection, antigen‐presenting cells (i.e., IgM+ B cells and macrophages) provide the first and secondary signals for T cells, initiating the Ca2+‐NFAT, MAPK/ERK, NF‐κB, and mTORC1 pathways, leading to IL‐2 transcription and T cell activation.