CASP4 and infection: In comparison with wild-type bacteria, infection with the complemented PA14 ΔflgK pUCP19-flgK and PA14 ΔpopB pUCP19-popB strains restored to varying degrees the protein levels of TLR4, TLR5, NLRC4, caspase-4 and mature IL-1β and IL-18 (Figure 2B, Supplementary Table 2).