Construction of sieve tubes has long been known, but only on the ultrastructure of recent reports allow you to fully understand how these creatures are well adapted to its function, ranging from reducing resistance to the flow of juice floemowego, by withstanding high pressures, up to safeguards against leakage of contents in the event of damage from the attack and pathogens. Floemowy juice contains not only sugars and ions, but also hormones, proteins and nucleic acids. These compounds are involved in signaling, as well as systemic immune reaction against viruses.

The phenomenon of multidrug resistance is a common cause of failure of cancer chemotherapy. Tested a number of cellular mechanisms that affect the cytotoxic effects of anticancer drugs. One of the most intensively studied forms of cell resistance to therapy resistance is caused by overexpression of membrane glycoproteins. Some membrane proteins responsible for membrane transport of drugs and genes encoding them have been identified and characterized. They play an important role in reducing the intracellular levels of drugs.