Disorazole C1 causes irreversible growth inhibition. A549 cells
were treated for 1 h with 10 nM disorazole C1, 1 μM nocodazolem,
or DMSO vehicle followed by either washout of compound (wash) or continuous
exposure to compound (contin) for 1, 24, 48, 72, and 144 h. Live cells were
counted by trypan blue exclusion. The number of viable cells (trypan blue
negative) is graphed as the percentage of viable cells per milliliter
normalized to the DMSO control. Data are representative of two independent
experiments. B, A549 cells were incubated with doxorubicin (50 nM) or
disorazole C1 (2 or 10 nM) for 24 (open bars) or 48 (black bars) h,
and apoptosis was determined with a TUNEL assay. n = 3; bars,
S.E.M.