The sensitivity to Cry5B of animals mutant for the three ER stress response pathways was quantitatively assessed using a dosedependent lethality assay ( Figure 2B ). From these data, an LC 5s s (lethal concentrations at which 50% of the animals die) were obtained (Table 1) . Our quantitative results confirm that ire-1(v33) and xbp-1(zc12) mutant animals are statistically more sensitive to PFT than wild type animals (Table 1 ) and thus are Hpo relative to wild type (caution is called for in interpreting the ire-1(v33) data since many of these animals also have significant overt defects, e.g., developmental delays which prevents them from being as well synchronized at the start of the assay compared to the other strains [11] ). Our results indicate that atf-6(ok551) mutant animals are also Hpo, albeit to a lesser extent (2.8 vs. 5.8 fold increase in sensitivity for atf-6 vs. xbp-1). Although atf-6(ok551) hypersensitivity was not discerned with the plate assay, it is likely that the quantitative lethality assay is a more sensitive test for Cry5B hypersensitivity than the qualitative plate assay. In contrast to xbp-1 and atf-6 mutant animals, the sensitivity of pek-1(ok275) mutant animals is not statistically different from that of wild-type animals ( Table 1) .