Celastrol-caused Hsp90 inhibition and ER-Stress response let to increase of Noxa.

<p><b>A and B.</b> Bel-7402 and HepG2 cells were treated 1.25, 2.5, 5 µM Celastrol for 3 h, lysates were harvested and immunobloted with Hsp70, p-ERK, CDK4 and UB antibodies. <b>C.</b> HepG2 cells were treated 1.25, 2.5, 5 µM Celastrol for 3 h, lysates were harvested and immunobloted with p-eIF2a and ATF4. <b>D.</b> HepG2 cells were treated with 1.25 µM Celastrol or plus 10 µM ABT-737 for 12 h. Noxa mRNA levels were determined by real-time RT-PCR relative to GAPDH as an internal control. <b>E.</b> HepG2 cells were transfected with ATF4 siRNA according to manufacturer’s recommendations. Forty-eight hours after transfection, lysates were harvested and immunobloted with ATF4 antibody. <b>F.</b> Cells were treated with 1.25 µM Celastrol for 24 h. Noxa mRNA levels were determined by real-time RT-PCR relative to GAPDH as an internal control. The results were similar in at least three independent experiments. *, <i>p</i><0.05.