Figure 9. Proposed schematic representation of SP action.

The scheme shows SP effects on sensitive cancer cells and supposed mechanisms of action as derived from the integration between experimental data and literature background. The alteration of ROCK/HDAC6 pathways leads to tubulin abnormalities and this could be responsible of mitotic catastrophe in the major part of treated cells (∼80 %). Longer incubation with SP leads to induction of premature senescence through p53/p21 pathway activation in a significant amount of surviving cells (∼15 %).