CASP4 and Salmonella Infections: To test the relative contribution of both caspases-4 and 5 to NAIP/NLRC4-independent inflammasome responses during Salmonella infection of THP-1 macrophages, we treated WT, NAIP-/- and NLRC4-/- THP-1s with siRNAs targeting CASP4, CASP5, or both, achieving ~70–90% knockdown efficiency at the mRNA level (S8 Fig), and subsequently assayed for IL-1β secretion in response to WT Stm.