Using the Vesicular Stomatitis Virus (VSV) as a “hijacker” of the endocytic pathway, Jean Gruenberg and his colleagues demonstrated that intralumenal vesicles present within multivesicular endosomes are able to undergo back-fusion with the limiting membrane of these organelles, thus releasing their content into the cytoplasm, a process regulated by the ESCRT-related proteins TSG101 and ALIX, and since shown to be exploited by various other invaders of the cells such as the Anthrax toxin, and several other viruses.