CDC25i and CDK1/2i, but not CDC7i, prevent pHH3 and γH2AX
from SN38 with CHK1i or WEE1i. (a) MDA-MB-231 cells were incubated
with SN38 for 24 h and then CHK1i or WEE1i from 24 to 30 h. Additionally,
CDC25i, CDK1/2i, or CDC7i was administered concurrently with CHK1i
or WEE1i as indicated. Whole cell extracts were probed for the indicated
proteins by Western blotting. Black arrows indicate bands relatively
resistant to CVT-313, and gray arrows indicate bands very sensitive
to CVT-313; these arrows highlight the same bands noted in Figure 4b. (b) MDA-MB-231
cells were incubated with SN38 for 24 h. Cyclin E protein was immunoprecipitated,
and the indicated proteins were probed by Western blotting.