Testing for endocytosis in plants.

For many years endocytosis has been regarded with great scepsis by plant physiologists. Although now generally accepted, care must still be taken with experiments designed to demonstrate endocytic uptake at the plasma membrane. We have taken a critical look at the various agents which are in use as markers for plant endocytosis, pointing out pitfalls and precautions which should be taken. We also take this opportunity to introduce the tyrphostins--tyrosine kinase inhibitors--, which also seem to prevent endocytosis in plants.