Figure 4.

HSF1 is required for cytoprotective effect of HS pre-conditioning but not for the cytotoxic effect of concurrent HS and TNF-α treatment. (A) WT and HSF1-knockout (KO) mouse embryonic fibroblasts (MEFs) were preconditioned with 2-hour 42°C HS beginning at the indicated time, treated with 4 ng/ml TNF-α and concurrent 2-hour HS, incubated for an additional 2 hours at 37°C, and cell survival was assessed by crystal violet staining. Control-treated cells were incubated in parallel at 37°C without TNF-α or HS. (B) WT and HSF1-KO MEFs were incubated with or without 4 ng/ml TNF-α and with or without a concurrent 2-hour 42°C HS, incubated at 37°C for an additional 2 hours, and cell survival was assessed by crystal violet staining. Means (±SE) of four experiments are shown. (A) WT is significantly different from HSF1-KO (P = 0.04 by MANOVA). (B) *P < 0.05 versus all three other treatments.