Late endosomes (red) scatter to the cell periphery when the p14 adaptor is missing.

Receptors keep signaling long after they are endocytosed thanks to a variety of adaptor proteins. Now, Teis et al. show on page 861 that the loss of p14, a protein that helps attach active MAP kinase to endosomes, results in endosome positioning defects, cell cycle problems, and death.

Mice lacking p14 died as embryos. Fibroblasts from the embryos had normal early endosomes but, compared with wild-type cells, twice as many of their late endosomes and lysosomes were located far from the nucleus, and degradation of internalized EGF receptor was half as efficient.

Epidermal-specific deletion of p14 resulted in mice that were born alive but died soon after from dehydryation. EGF receptors, normally found only in basal cell layers, were not degraded properly and were therefore expressed even in suprabasal cell layers....

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