a, In vitro IKK-kinase activity in TNFα-treated Sharpincpdm/Sharpincpdm MEFs stably transduced with non-targeting (control) or HOIL-1L shRNA. b, c, Defect of TNFα-induced IκBα degradation and translocation of p65 in Sharpincpdm/Sharpincpdm MEFs stably transduced with HOIL-1L shRNA. (n = 19–23) d, e, Impaired NF-κB activation in primary B cells or macrophages of Sharpincpdm/Sharpincpdm stimulated with CD40L or LPS. e, f, g, Reduced capacity of Sharpincpdm/Sharpincpdm macrophages to secrete TNFα and MCP-1 in response to LPS. TNFα ELISA; n=5, MCP-1 ELISA; n=4. Results in c, f and g are shown as means and s.e.m. *P < 0.0001, determined by the Student's t-test.