The four digestive processes mediated by the lysosome (from the upper left corner clockwise).

(i) Specific receptor-mediated endocytosis, (ii) pinocytosis (non-specific engulfment of cytosolic droplets containing extracellular fluid), (iii) phagocytosis (of extracellular particles), and autophagy; (iv) microautophagy of intracellular proteins under basal conditions, and (v) macroautophagy of organelles under stress) (with permission from Nature Publishing Group; published originally in Ciechanover⁸³).