Answer
Vincristine prevents the mitotic spindle from properly pulling apart the sister chromatids. Doxorubicin stop she process for protein synthesis from happening early on in the cell.
Work Step by Step
A damaged mitotic spindle would likely not be able to pull apart the sister chromatids to the opposite poles so that the two daughter cells can be formed. Even if the mitotic spindle was able to pull apart sister chromatids, it may not be able to do it correctly and the resulting daughter cells could have too many or too few chromosomes, could fail to thrive.
Blocking RNA synthesis means that the copy of the DNA cannot be made and there will be no instructions for the ribosomes and the tRNA to use for protein synthesis. Without new proteins, the cell does not have what it needs for cellular activities, such as repairing itself, metabolism, or growing.
