FIGURE 2: Cytokine secretion in response to LPS stimulation. There are two pathways for the LPS-initiated secretion of cytokines. In the conventional pathway, LPS binds to its cognate cell surface receptor, TLR4. The activation of TLR4 leads to the activation of NF-kB as well as HIF1α, the latter of which is mediated by mitochondrial dysfunction. Both NF-kB and HIF1α are involved in the expression cytokines as well as inflammasome components. Inflammasomes, comprising NLRP3, ASC, and Cas-1 for example, are involved in the activation of Cas-1. In an unconventional pathway, LPS binds directly to cytoplasmic Cas-11, which cleaves gasdermin to form a pore in the plasma membrane.