Many cellular processes, including embryogenesis (1–4), gene expression (5), cell cycle (6),
programmed cell death (7), intracellular protein targeting (8) and endocrine/neural functions
(9–13) are regulated by limited proteolysis of precursor proteins (14, 15). These functions
are carried out by proteolytic enzyme families that are strategically localized within cells or
on cell surfaces (3, 5–7, 9, 10). This review focuses on the serine proteases that process
protein precursors (proproteins) traversing the secretory pathway (for recent reviews, see …