What is the primary function of microtubule spindle inhibitors like paclitaxel?

The primary function of microtubule spindle inhibitors, such as paclitaxel, is to induce cell cycle arrest during mitosis. Paclitaxel functions by stabilizing the microtubules and preventing their depolymerization, which effectively halts the normal mitotic spindle formation necessary for chromosomal segregation during cell division. This blockage leads to an accumulation of cells in the mitotic phase, thus disrupting the cell cycle and preventing further division.

While growth inhibition can be a consequence of cell cycle arrest, the essential mechanism by which paclitaxel exerts its antitumor effects revolves around its ability to interfere with spindle dynamics during mitosis. The drug does not directly promote apoptosis nor does it enhance cellular division; rather, it creates conditions that lead cells to ultimately undergo programmed cell death due to the inability to successfully complete mitosis.