CASP4 and cervical carcinoma: PMN-Spt from human neutrophils stimulated with 100 nM fMLP induced an endoplasmic reticulum (ER) stress response in HeLa cervical cancer cells as assessed by the analysis of a number of ER stress-associated markers, including phosphorylation of PERK (p-PERK), phosphorylation of eukaryotic translation initiation factor 2α-subunit (p-eIF2α) and activation of caspase-4 (Fig. 4a).