Extracted from Taxus brevifolia barks.

Inhibitor of protein kinase C (PKC) ζ; attached to cell permeabilisation Antennapedia domain vector peptide. Consists of amino acids 113 - 129 of PKC ζ pseudosubstrate domain linked by a disulphide bridge to the Antennapedia domain vector peptide. The Antennapedia peptide is actively taken up by intact cells, at 4 or 37°C, ensuring rapid and effective uptake of the inhibitor peptide. Once inside the cell, the disulphide bonds are subjected to reduction in the cytoplasm leading to release of the inhibitor peptide. Induces mast cell degranulation by a PKC ζ-independent pathway.

Ondansetron is a serotonin 5-HT3 receptor antagonist used mainly as an antiemetic.