拉 丁 名：Chinese yew
Production Name:Paclitaxel or Taxol
Original plant:Chinese yew
Appearance: White to off-white powder
Solubility:Insoluble in water, soluble in alcoho
Description:Paclitaxel-treated cells have defects in mitotic spindle assembly, chromosome segregation, and cell division. Unlike other tubulin targeted drugs such as colchicine that inhibit microtubule assembly, however, paclitaxel stabilizes the microtubule polymer and protects it from disassembly. The inability of the chromosomes to achieve a metaphase spindle configuration leads to a mitotic block in which there is prolonged activation of the mitotic checkpoint with the subsequent triggering of apoptosis or slippage back into the G1-phase of the cell cycle without cell division.The ability of paclitaxel to inhibit spindle function is generally attributed to its suppression of microtubule dynamics;but recent studies have demonstrated that suppression of dynamics occurs at concentrations lower than those needed to block mitosis. At the higher antimitotic concentrations, paclitaxel appears to act by suppressing microtubule detachment from centrosomes, a process normally activated during mitosis.The binding site for paclitaxel has been shown to reside on the beta-tubulin subunit.