(A) Bortezomib-resistant cell line was not resistant to SOP11. WT or
bortezomib-resistant (BTZR) RPE1 cells were treated with different
concentrations of SOP11 or BTZ for 72 hours and then mixed with CellTiter-Glo
reagent to estimate cell proliferation. Measured luminescence values were
normalized to DMSO control, and data were fitted to a dose–response
equation to determine the GI50 (50% cell growth inhibition). Error
bars represent s.d., n = 4 wells, from 1 representative of 3 independent
experiments. Error bars are too small to be visualized for some data points in
this graph. (B) ETPs induce apoptosis. HCT116 cells were treated with 10
μM of the indicated ETPs or CZM for 24 hours. Western blot analyses of
cell lysates were performed with antibodies against PARP1, γH2AX, and
GAPDH, as indicated. See also Table S2.