FIG. 3.

Effect of heat shock treatment on the activity of Akt (A), ERK1 and -2 (B), p38 (C), and JNK (D) kinases in fibroblasts. IMR90 fibroblasts were exposed to heat shock (45°C) for the indicated time periods and were then transferred to normal temperature (37°C, recovery). (A to C) The activity of the Akt, ERK, and p38 kinases was measured by immunoblotting with antibodies to phosphorylated (active) kinases. (D) The activity of JNK was assayed by c-Jun phosphorylation as described in Materials and Methods.