Fig. 5.

SAHA-induced cleavage of HSP90 is mediated by caspase 10. a K562 cells were untreated or treated with 20 mM of NAC for 1 h, followed by treatment with SAHA (5 μM) for 24 h. The cell lysates were incubated with indicated colorimetric caspase substrates, and color development was measured at a wavelength of 400 nm. The caspase activity values were normalized with respective background values. b K562 cells were untreated or treated 1 μM of caspase family inhibitors for 1 h, followed by treatment with SAHA (5 μM) for 24 h. The cell lysates were subjected to Western blot analysis. c K562 cells were untreated or treated with 1 μM of caspase 8 inhibitor for 1 h and then treated with 5 μM of SAHA for 24 h. The cell lysates were incubated with caspase 10 colorimetric substrate to measure the activity of caspase 10. The caspase activity values were normalized with control value. *P < 0.05, **P < 0.01. Caspase 2 inhibitor, z-VDVAD-fmk; caspase 3 inhibitor, z-DEVD-fmk; caspase 6 inhibitor, z-VEID-fmk; caspase 8 inhibitor, z-IETD-fmk; caspase 10 inhibitor, z-AEVD-fmk