The protein clathrin is best known for its important role in coated vesicle formation and its triskelion form. The formation of coated vesicles is an uninterrupted and essential process in non-dividing cells. However, clathrin also performs a vital function of a different sort in cells undergoing mitosis. The enzymes contained in peroxisomes, such as catalase and D-amino acid oxidase, chiefly function to rid cells of toxic substances, particularly hydrogen peroxide, but also alcohol and other damaging compounds. The dynamic behavior of coated vesicles was visualized in the digital video sequences in this section by fusing mEmerald to clathrin in a specimen of fox lung cells. The peroxisomes were labeled with mCherry.