What common step do all forms of endocytosis share?

1. Endocytosis is a type of active transport that moves large molecules, parts of cells and even whole cells into a cell. 2. In every variation the plasma membrane invaginates, forming a pocket around the target particle. 3. The pocket pinches off, so the particle ends up inside a newly created intracellular vesicle formed from the plasma membrane. 4. A large particle cannot pass through the membrane at all, even with energy supplied, so no channel or carrier route is available to it. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 5 "Structure and Function of Plasma Membranes", section 5.4 Bulk Transport_