Figure 5.

The process of methuosis. Methuosis is caused by hyperactive macropinocytosis. Macropinocytosis is a clathrin-independent endocytosis pathway. When macropinocytosis is activated, macropinosomes are produced, and macropinosomes further merge into larger vacuoles. Macropinosome does not participate in the recycling pathway of receptor-mediated endocytosis, and only few of the macropinosome is fused with lysosomes. Therefore, numerous vacuoles build up inside the cell, which eventually leads to cell death. +/- represents participating or not participating in a later pathway. TrKA, Tyrosine kinase receptor A; METH, methamphetamine.