To investigate whether the role of IKKα in lung epithelial cells as an NSCLC tumor suppressor is linked with its essential function as the sole activating kinase of the noncanonical NF-κB/p52-RelB pathway, we knocked down NF-κB p52 expression in A549 and H1299 cells to assess their growth as tumor xenografts in NSG mice compared with their p52WT counterparts. The gene discussed is RELB; the disease is neoplasm.