NF-κB is a transcription factor regulated by genes that control immune and inflammatory responses, but NF-κB1 (p50) and NF-κB2 (p52) double-knockout (dKO) mice exhibited severe osteopetrosis and lacked osteoclasts, suggesting that NF-κB also directly controls osteoclast differentiation [13,14]. The gene discussed is NFKB1; the disease is osteopetrosis.