HSF - 1 acts downstream of DAF - 7 to regulate lifespan. HSF-1 is required for the long-lived phenotype of mutant animals defective for TGF-β signaling. HSF-1 deficiency suppresses longevity in daf-7(e1372) mutants. Kaplan-Meyer survival curves were generated by the SPSS software. For comparing daf-7(−) single mutants vs. daf-7(−); hsf-1(−) double mutants or the wild type; p<0.0001 (see the Methods).